GithubAction log format

[staabm]

while looking at #279 I got the idea that bashunit could benefit from a github action log format.

this means errors can show up in the "Files Changed"-tab of a pull request, like its already possible for a lot of other tools:

this could either be implemented natively - see e.g. how cs2pr does the output formatting

Alternatively you could instead implement a checkstyle based log formatter (see e.g. how php-cs-fixer implements it) and let the end user pipe the checkstyle format thru cs2pr. this would have the benefit that other tools which can consume checkstyle formatted error reports also benefit.