Provide Github actions (and other CI tools)

[javydekoning]

To support other CI's it would be best to move the logic from: https://github.com/majkinetor/au-packages-template/blob/master/.appveyor.yml#L73-L95 to update_all.ps1 (or another script/function).

Variables like branch name and commit message MUST be passed in as params, but it will make it much easier to understand the CI example.

I'm using Github actions, example here

[majkinetor]

Yeah, I don't like any programming in CI yaml BS so I generally agree. I was thinking about adding something like it via #18, but currently have no time for it, if you feel like it give it a go, otherwise, I am not sure when I'll be able to do it.