chore: unbreak base16-schemes-source submodule

Upstream deleted the `master` branch, replacing it with `main`:

    Fetching origin
    From https://github.com/chriskempson/base16-schemes-source
     - [deleted]         (none)     -> origin/master
       (refs/remotes/origin/HEAD has become dangling)
    remote: Enumerating objects: 16, done.
    remote: Counting objects: 100% (16/16), done.
    remote: Compressing objects: 100% (16/16), done.
    remote: Total 16 (delta 4), reused 0 (delta 0), pack-reused 0
    Unpacking objects: 100% (16/16), 6.91 KiB | 372.00 KiB/s, done.
     * [new branch]      main       -> origin/main

Remarkably, current `HEAD` of `main` isn't even a descendant of The
Branch Formerly known as `master`:

* vendor/base16-schemes-source e720724...944dbc7 (88):
  > Update list.yaml
  > Update README.md
  > Update list.yaml
  > Update README.md
  > Add files via upload
  < Add Sakura scheme (#73)
  < Add pinky scheme
  < Add Shades of Purple scheme (#75)
  < Add qualia to list.yaml
  < Merge pull request #79 from CosmosAtlas/patch-1
  < Add windows theme (#83)
  < Merge pull request #84 from casonadams/master
  < Merge pull request #85 from edunfelt/master
  < Merge pull request #66 from DanManN/master
  < Merge pull request #77 from akhsiM/master
  < Merge pull request #80 from Misterio77/patch-2
  < Merge pull request #81 from cveldy/master
  < Add Nebula scheme (#70)
  < Add "colors" color scheme (#68)
  < Add Pasque color scheme (#69)
  < Add vice scheme (#65)
  < Merge pull request #64 from kjakapat/master
  < Added darkmoss scheme (#55)
  < Merge pull request #63 from andreyvpng/master
  < Merge pull request #60 from tartansandal/tartansandal-add-dirtysea-scheme
  < Update list.yaml
  < Merge pull request #58 from jpfender/nord-fix
  < Re-enable summercamp
  < Merge pull request #53 from carloabelli/equilibrium-scheme
  < Merge pull request #62 from humanoid-colors/humanoid
  < Merge pull request #61 from ruler501/patch-1
  < Merge pull request #59 from Schnouki/patch-1
  < Merge pull request #56 from callerc1/master
  < Merge pull request #54 from cjayross/master
  < Merge pull request #52 from Whillikers/master
  < Re-add sandcastle and nova
  < Merge pull request #51 from alexmirrington/master
  < Merge pull request #50 from jssee/framer-scheme
  < Merge pull request #49 from base16-project/master
  < Merge pull request #42 from ajlende/patch-2
  < Merge pull request #41 from tealeg/patch-1
  < Merge pull request #40 from archmalet/master
  < Merge pull request #39 from jonleopard/master
  < Merge pull request #38 from jozip/master
  < Merge pull request #36 from aramisgithub/patch-3
  < Merge pull request #35 from h404bi/patch-1
  < Merge pull request #34 from metalelf0/master
  < Merge pull request #33 from aramisgithub/patch-1
  < Merge pull request #32 from piggyslasher/patch-1
  < Merge pull request #31 from joshyrobot/patch-1
  < Merge pull request #30 from mnussbaum/solarflare
  < Merge pull request #29 from hugodelahousse/patch-1
  < Merge pull request #28 from blockloop/patch-1
  < Merge pull request #27 from icyphox/master
  < Update README.md
  < Merge pull request #26 from AuditeMarlow/add-porple-scheme
  < Merge pull request #25 from gonsie/master
  < Merge pull request #24 from gidsi/master
  < Merge pull request #23 from mikebarkmin/patch-1
  < Merge pull request #22 from WhiteAbeLincoln/patch-1
  < Update list.yaml
  < Merge pull request #21 from ntpeters/patch-1
  < Merge pull request #19 from elnawe/master
  < Merge pull request #18 from Pokeconomist/patch-1
  < Merge pull request #14 from detly/master
  < Merge pull request #17 from purpleKarrot/master
  < Merge pull request #15 from Defman21/patch-3
  < Merge pull request #16 from stepchowfun/add-circus
  < Merge pull request #13 from 8-uh/patch-1
  < Merge pull request #12 from vic/patch-1
  < Merge pull request #11 from dawikur/master
  < Update README.md
  < Update list.yaml
  < Merge pull request #10 from jcornwall/master
  < Merge pull request #9 from mikebarkmin/patch-1
  < Merge pull request #8 from tilal6991/master
  < Merge branch 'joshwlewis-patch-1't push origin master
  < Merge branch 'cscorlt push origin masterey-patch-1'
  < t push origin masterMerge branch 'hartbit-master'
  < Merge pull request #4 from Defman21/patch-2
  < Merge pull request #3 from drzel/master
  < Merge branch 'refs/heads/pr/2'
  < Merge pull request #1 from atelierbram/atelier
  < Adds unclaimed schemes
  < Create README.md
  < Initial commit
  < Revert ":octocat: Added .gitattributes"
  < :octocat: Added .gitattributes

So here is a diff (via `cd vendor/base16-schemes-source && git diff
e720724..944dbc7`) for posterity:

```diff
diff --git a/README.md b/README.md
index c8feea9..28e0932 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,82 @@
 # Base16 Schemes Source
 By adding your repository to this list your scheme will be available to all Base16 Builders.
 All schemes added to this repository list **must** be released under the MIT (or more permissive) licence.
-Please list your scheme under https://github.com/chriskempson/base16#scheme-repositories so that others may find it easily.
+
+## Scheme Repositories
+
+To add your own scheme, submit a pull request and add your repository to the list below. **Repository naming scheme: base16-[scheme-name]-scheme** (with dashes as separators).
+
+### Official Schemes
+* [Default](https://github.com/chriskempson/base16-default-scheme) maintained by [chriskempson](https://github.com/chriskempson)
+
+### Community Contributed Schemes
+* [Apprentice](https://github.com/casonadams/base16-apprentice-scheme) maintained by [casonadams](https://github.com/casonadams)
+* [Atelier](https://github.com/atelierbram/base16-atelier-schemes) maintained by [atelierbram](https://github.com/atelierbram)
+* [Atlas](https://github.com/ajlende/base16-atlas-scheme) maintained by [ajlende](https://github.com/ajlende)
+* [Black Metal](https://github.com/metalelf0/base16-black-metal-scheme) maintained by [metalelf0](https://github.com/metalelf0)
+* [Brogrammer](https://github.com/piggyslasher/base16-brogrammer-scheme) maintained by [piggyslasher](https://github.com/piggyslasher)
+* [Brush Trees](https://github.com/whiteabelincoln/base16-brushtrees-scheme) maintained by [whiteabelincoln](https://github.com/whiteabelincoln)
+* [Circus](https://github.com/stepchowfun/base16-circus-scheme) maintained by [stepchowfun](https://github.com/stepchowfun) and [ewang12](https://github.com/ewang12)
+* [Classic](https://github.com/detly/base16-classic-scheme) maintained by [detly](https://github.com/detly)
+* [Codeschool](https://github.com/blockloop/base16-codeschool-scheme) maintained by [blockloop](https://github.com/blockloop)
+* [Colors](https://github.com/hakatashi/base16-colors-scheme) maintained by [hakatashi](https://github.com/hakatashi)
+* [Cupertino](https://github.com/Defman21/base16-cupertino) maintained by [Defman21](https://github.com/Defman21)
+* [DanQing](https://github.com/CosmosAtlas/base16-danqing-scheme) maintained by [CosmoAtlas](https://github.com/CosmosAtlas)
+* [Darcula](https://github.com/casonadams/base16-darcula-scheme) maintained by [casonadams](https://github.com/casonadams)
+* [Darkviolet](https://github.com/ruler501/base16-darkviolet-scheme) maintained by [ruler501](https://github.com/ruler501)
+* [Dracula](https://github.com/dracula/base16-dracula-scheme) maintained by [mikebarkmin](https://github.com/mikebarkmin)
+* [Equilibrium](https://github.com/carloabelli/base16-equilibrium-scheme) maintained by [carloabelli](https://github.com/carloabelli)
+* [Espresso](https://github.com/alexmirrington/base16-espresso-scheme) maintained by [alexmirrington](https://github.com/alexmirrington)
+* [Eva](https://github.com/kjakapat/base16-eva-scheme) maintained by [kjakapat](https://github.com/kjakapat)
+* [Framer](https://github.com/jssee/base16-framer-scheme) maintained by [jssee](https://github.com/jssee)
+* [Fruit Soda](https://github.com/jozip/base16-fruit-soda-scheme) maintained by [jozip](https://github.com/jozip)
+* [Gigavolt](https://github.com/Whillikers/base16-gigavolt-scheme) maintained by [Whillikers](https://github.com/Whillikers)
+* [Github](https://github.com/Defman21/base16-github-scheme) maintained by [Defman21](https://github.com/Defman21)
+* [Gruvbox](https://github.com/dawikur/base16-gruvbox-scheme) maintained by [dawikur](https://github.com/dawikur)
+* [Hardcore](https://github.com/callerc1/base16-hardcore-scheme) maintained by [callerc1](https://github.com/callerc1)
+* [Helios](https://github.com/reyemxela/base16-helios-scheme) maintained by [reyemxela](https://github.com/reyemxela)
+* [Heetch](https://github.com/tealeg/base16-heetch-scheme) maintained by [tealeg](https://github.com/tealeg)
+* [Horizon](https://github.com/michael-ball/base16-horizon-scheme) maintained by [michael-ball](https://github.com/michael-ball)
+* [Humanoid](https://github.com/humanoid-colors/base16-humanoid-schemes) maintained by [tasmo](https://github.com/tasmo)
+* [iA](https://github.com/aramisgithub/base16-ia-scheme) maintained by [aramisgithub](https://github.com/aramisgithub)
+* [Icy](https://github.com/icyphox/base16-icy-scheme) maintained by [icyphox](https://github.com/icyphox)
+* [Kimber](https://github.com/akhsiM/base16-kimber-scheme) maintained by [Mishka](https://github.com/akhsiM)
+* [Materia](https://github.com/Defman21/base16-materia) maintained by [Defman21](https://github.com/Defman21)
+* [Material Theme](https://github.com/ntpeters/base16-materialtheme-scheme) maintained by [ntpeters](https://github.com/ntpeters)
+* [Material Vivid](https://github.com/joshyrobot/base16-material-vivid-scheme) maintained by [joshyrobot](https://github.com/joshyrobot)
+* [Mellow](https://github.com/gidsi/base16-mellow-scheme) maintained by [gidsi](https://github.com/gidsi)
+* [Mexico-Light](https://github.com/drzel/base16-mexico-light-scheme) maintained by [drzel](https://github.com/drzel)
+* [Nebula](https://github.com/Misterio77/base16-nebula-scheme) maintained by [Misterio77](https://github.com/Misterio77)
+* [Nord](https://github.com/8-uh/base16-nord-scheme) maintained by [8-uh](https://github.com/8-uh)
+* [Nova](https://github.com/gessig/base16-nova-scheme) maintained by [gessig](https://github.com/gessig)
+* [One Light](https://github.com/purpleKarrot/base16-one-light-scheme) maintained by [purpleKarrot](https://github.com/purpleKarrot)
+* [Onedark](https://github.com/tilal6991/base16-onedark-scheme) maintained by [tilal6991](https://github.com/tilal6991)
+* [Outrun](https://github.com/hugodelahousse/base16-outrun-schemes) maintained by [hugodelahousse](https://github.com/hugodelahousse)
+* [PaperColor](https://github.com/jonleopard/base16-papercolor-scheme) maintained by [jonleopard](https://github.com/jonleopard)
+* [Pasque](https://github.com/Misterio77/base16-pasque-scheme) maintained by [Misterio77](https://github.com/Misterio77)
+* [pinky](https://github.com/b3nj5m1n/base16-pinky-scheme) maintained by [b3nj5m1n](https://github.com/b3nj5m1n)
+* [Porple](https://github.com/AuditeMarlow/base16-porple-scheme) maintained by [AuditeMarlow](https://github.com/AuditeMarlow)
+* [Purpledream](https://github.com/archmalet/base16-purpledream-scheme) maintained by [archmalet](https://github.com/archmalet)
+* [Qualia](https://github.com/isaacwhanson/base16-qualia-scheme) maintained by [isaacwhanson](https://github.com/isaacwhanson)
+* [Rebecca](https://github.com/vic/base16-rebecca) maintained by [vic](https://github.com/vic)
+* [Rosé Pine](https://github.com/edunfelt/base16-rose-pine-scheme) maintained by [edunfelt](https://github.com/edunfelt)
+* [Sagelight](https://github.com/cveldy/base16-sagelight-scheme) maintained by [cveldy](https://github.com/cveldy)
+* [Sakura](https://github.com/Misterio77/base16-sakura-scheme) maintained by [Misterio77](https://github.com/Misterio77)
+* [Sandcastle](https://github.com/gessig/base16-sandcastle-scheme) maintained by [gessig](https://github.com/gessig)
+* [Shades of Purple](https://github.com/ahmadawais/base16-shades-of-purple) maintained by [Ahmad Awais](https://github.com/ahmadawais) and [Demartini](https://github.com/demartini)
+* [Silk](https://github.com/Misterio77/base16-silk-scheme) maintained by [Misterio77](https://github.com/misterio77)
+* [Snazzy](https://github.com/h404bi/base16-snazzy-scheme) maintained by [h404bi](https://github.com/h404bi)
+* [Solarflare](https://github.com/mnussbaum/base16-solarflare-scheme) maintained by [mnussbaum](https://github.com/mnussbaum)
+* [Solarized](https://github.com/aramisgithub/base16-solarized-scheme) maintained by [aramisgithub](https://github.com/aramisgithub)
+* [Summercamp](https://github.com/zoefiri/base16-summercamp) maintained by [zoe firi](https://github.com/zoefiri)
+* [Summerfruit](https://github.com/cscorley/base16-summerfruit-scheme) maintained by [cscorley](https://github.com/cscorley)
+* [Synth Midnight](https://github.com/michael-ball/base16-synth-midnight-scheme) maintained by [michael-ball](https://github.com/michael-ball)
+* [Tender](https://github.com/DanManN/base16-tender-scheme) maintained by [DanManN](https://github.com/DanManN)
+* [Twilight](https://github.com/hartbit/base16-twilight-scheme) maintained by [hartbit](https://github.com/hartbit)
+* [Unikitty](https://github.com/joshwlewis/base16-unikitty) maintained by [joshwlewis](https://github.com/joshwlewis)
+* [Vice](https://github.com/Thomashighbaugh/base16-vice-scheme) maintained by [Thomashighbaugh](https://github.com/Thomashighbaugh)
+* [Windows](https://github.com/C-Fergus/base16-windows-scheme) maintained by [C-Fergus](https://github.com/C-Fergus)
+* [Woodland](https://github.com/jcornwall/base16-woodland-scheme) maintained by [jcornwall](https://github.com/jcornwall)
+* [Zenburn](https://github.com/elnawe/base16-zenburn-scheme) maintained by [elnawe](https://github.com/elnawe)
+* [XCode Dust](https://github.com/gonsie/base16-xcode-dusk-scheme) maintained by [gonsie](https://github.com/gonsie)
+* [Old Unclaimed Schemes](https://github.com/chriskempson/base16-unclaimed-schemes) - If your scheme is in this repository, please give it a new home!
diff --git a/list.yaml b/list.yaml
index d0e6116..6382e24 100644
--- a/list.yaml
+++ b/list.yaml
@@ -1,4 +1,7 @@
-# Please order list alphanumerically
+# Offical Base16 Schemes
+default: https://github.com/chriskempson/base16-default-schemes
+
+# Community Contributed Schemes - Please order list alphanumerically
 apprentice: https://github.com/casonadams/base16-apprentice-scheme
 atelier: https://github.com/atelierbram/base16-atelier-schemes
 atlas: https://github.com/ajlende/base16-atlas-scheme
@@ -14,7 +17,6 @@ darcula: https://github.com/casonadams/base16-darcula-scheme
 darkmoss: https://github.com/avanzzzi/base16-darkmoss-scheme
 darkviolet: https://github.com/ruler501/base16-darkviolet-scheme
 danqing: https://github.com/CosmosAtlas/base16-danqing-scheme
-default: https://github.com/chriskempson/base16-default-schemes
 dirtysea: https://github.com/tartansandal/base16-dirtysea-scheme
 dracula: https://github.com/dracula/base16-dracula-scheme
 edge: https://github.com/cjayross/base16-edge-schemes
@@ -25,6 +27,7 @@ framer: https://github.com/jssee/base16-framer-scheme
 fruit-soda: https://github.com/jozip/base16-fruit-soda-scheme
 gigavolt: https://github.com/Whillikers/base16-gigavolt-scheme
 github: https://github.com/Defman21/base16-github-scheme
+gruber: https://github.com/nimaipatel/base16-gruber
 gruvbox: https://github.com/dawikur/base16-gruvbox-scheme
 hardcore: https://github.com/callerc1/base16-hardcore-scheme
 heetch: https://github.com/tealeg/base16-heetch-scheme
@@ -40,6 +43,7 @@ material-vivid: https://github.com/joshyrobot/base16-material-vivid-scheme
 mellow: https://github.com/gidsi/base16-mellow-scheme
 mexico-light: https://github.com/drzel/base16-mexico-light-scheme
 nebula: https://github.com/Misterio77/base16-nebula-scheme
+nord: https://github.com/spejamchr/base16-nord-scheme
 nova: https://github.com/gessig/base16-nova-scheme
 onedark: https://github.com/tilal6991/base16-onedark-scheme
 one-light: https://github.com/purpleKarrot/base16-one-light-scheme
@@ -65,7 +69,6 @@ summerfruit: https://github.com/cscorley/base16-summerfruit-scheme
 synth-midnight: https://github.com/michael-ball/base16-synth-midnight-scheme
 tango: https://github.com/Schnouki/base16-tango-scheme
 tender: https://github.com/DanManN/base16-tender-scheme
-tomorrow: https://github.com/chriskempson/base16-tomorrow-scheme
 twilight: https://github.com/hartbit/base16-twilight-scheme
 unikitty: https://github.com/joshwlewis/base16-unikitty
 vice: https://github.com/Thomashighbaugh/base16-vice-scheme
@@ -77,9 +80,3 @@ zenburn: https://github.com/elnawe/base16-zenburn-scheme

 # If your scheme is in this repository, please give it a new home!
 unclaimed: https://github.com/chriskempson/base16-unclaimed-schemes
-
-# NOTE: the original repo at https://github.com/8-uh/base16-nord-scheme
-# is based on another color scheme and doesn't quite match. There was a
-# fork to improve the colors, so that's what we're using. If the original
-# repo ever gets updated, we can switch back to that.
-nord: https://github.com/spejamchr/base16-nord-scheme
```

.gitmodules

@@ -6,6 +6,7 @@
  path = aspects/nvim/files/.config/nvim/pack/bundle/opt/applescript.vim
  url = https://github.com/vim-scripts/applescript.vim.git
 [submodule "base16-schemes-source"]
+ branch = main
  path = vendor/base16-schemes-source
  url = https://github.com/chriskempson/base16-schemes-source.git
 [submodule "base16-templates-source"]