CI for PyGriffin

Shriwise, Patrickrequested to merge
pygriffin-ci-rebase into pygriffin_initial

This MR includes CI for PyGriffin. It also includes a small fix in the expected output of one of the PyGriffin prerun tests.

I've included a fix for subprocess.check_output returning a bytes object in this branch as well so we can run CI fully with this branch.

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