[BUILD] Automatic dependency updates

[kbudde]

There are currently several different dependencies in prometheus-msteams: github actions, go libraries and docker.
Keeping all of them up to date is tedious.

Having a tool like dependabot or renovate simplifies this process.

For the github actions it would be worth considering using the commit hash instead of a version number. This ensures that all builds remain reproducible. Go offers similar functionality by default via go.sum.
Renovate supports this for github-actions(doc). Not sure about dependabot.

[ckotzbauer]

👍 for Renovate (better configurable than dependabot)

[kbudde]

OK, sound like renovate.
We should also run the tests in our pipelines to ensure that nothing is breaking. There are some outdated packages.

[zhan9san]

It is fixed in #283