Use the checks api

[adangel]

See https://docs.github.com/en/rest/reference/checks

The advantage over the currently implemented build annotations (#7) is, that we can mark the build as failed directly. This would make the extra build step, to make the build fail based on the number of violations (exit 1), superfluous. Then this could be a built-in feature which can be enabled/disabled via a input parameter.