Add unit tests for slack/prometheus behaviour

[evrardjp]

As our automated (in github actions) release testing only does pure functional testing, we might miss some of the extra features kured is providing, like messaging notifications or prometheus integration.

To avoid issues creeping in into the release, we should probably test those integrations into each PR.
By testing those into PRs, we can also safely bump dependabot updates. (This could technically allow an auto-merge of dependabot dependencies in the future, as long as they are not client-go/kubectl related).

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This issue was automatically considered stale due to lack of activity. Please update it and/or join our slack channels to promote it, before it automatically closes (in 7 days).

[github-actions]

This issue was automatically considered stale due to lack of activity. Please update it and/or join our slack channels to promote it, before it automatically closes (in 7 days).