Transition to GitHub Actionsgood first bughelp wanted
Description
We hard-coded the action call with one version https://github.com/mozilla/DeepSpeech/blob/5f566f442541d76f320ee081294cdef980c361d1/.github/workflows/macOS-amd64.yml#L54-L86 it would be nice to:
- use a matrix for all versions we can
- add new
train-test-modeljobs using a matrix as well to ensure test coverage