Fix kured slack notification missing username

[bengtfredh]

Kured slack notification do not send with username. All messages get added as user Kured.

Looks like this need to be changed:
--slack-hook-url string slack hook URL for reboot notfications [deprecated in favor of --notify-url]

Looks like this is a know issue:
kubereboot/kured#482

Probably smart to upgrade kured to latest version and change to use --notify-url. Check if this help the issue.

[bengtfredh]

Latest kured chart version is 2.12.0 (16 Mar, 2022)

[bengtfredh]

Bumped kured chart to v2.12.0 at/tt/yt

[bengtfredh]

Upgrade did not help. Same result - slack username is not respected and message show as sendt from Kured.
Will try to change to use --notify-url next

[bengtfredh]

Discovered chart version now is 2.12.1 with app version 1.9.2.
Will upgrade and test.

[bengtfredh]

Upgrade to 2.12.1 did not help.
Next I try to change from --slack-hook-url to --notify-url

[bengtfredh]

Switch to --notify-url did not make any difference. Slack username not respected.

[bengtfredh]

Done some reading, and there is changes in kured and shoutrrr. We probably need to move to shoutrrr new url format. Like descibed here:
https://containrrr.dev/shoutrrr/v0.5/services/slack/

For now we can probably use following format, which will be upgraded to new format by shoutrrr.

--notify-url=slack://watchtower@token-a/token-b/token-c

[bengtfredh]

This url worked as expected.