GitHub Action for nogil/python

[jimkring]

I created a GitHub Action to make it really easy to run and test one's github project code running in nogil (since installing nogil on a github runner isn't trivial, obvious, or fast).

My hope is that this is helpful for getting people to start testing nogil (and their code running in nogil) and providing feedback.

-> https://github.com/marketplace/actions/nogil-python

And, here's a small test project that shows uses it:
https://github.com/jimkring/action-python-nogil-test