ci: bump actions/checkout from 2 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/integration.yaml

@@ -25,7 +25,7 @@ jobs:
  df -h
 
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
 
  - uses: actions/setup-go@v2
  with:

.github/workflows/markdownlint.yaml

@@ -10,7 +10,7 @@ jobs:
  runs-on: ubuntu-latest
  steps:
  - name: Checkout repository
- uses: actions/checkout@v2
+ uses: actions/checkout@v4
  - uses: DavidAnson/markdownlint-cli2-action@v9
  with:
  command: config

.github/workflows/test.yaml

@@ -18,7 +18,7 @@ jobs:
  runs-on: ubuntu-latest
  steps:
  - name: Checkout
- uses: actions/checkout@v3
+ uses: actions/checkout@v4
 
  - uses: actions/setup-go@v2
  with: