feat: add pytest as a dev dependency and a github CI workflow #270

nice of you to add a test, but currently there is no runner of this in CI or otherwise.
this would be good to have, should we have another PR adding this cleanly?
that could include this test file, dev dependency added to pyproject for poetry and a github workflow that would run on every PR touching the python files.

Originally posted by @kyteinsky in #257 (comment)