Update python-package.yml

[mr-fuller]

I did some digging and it looked like maybe the workflows need to be updated, possibly due to the switch to Node16 instead of Node12 (https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/). It looked like the workflows were failing to even install python before running any tests on the package code.

I don't know anything about the workflows or how to test if this fixes anything. I just changed a few things based on the starter workflow from github's python package guide (https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python).

Edit: the workflows failing in (#126) had errors about not finding python versions and warnings about the deprecation. I think the changes I am suggesting only address the warnings, not the errors.

Edit 2: based on this comment/thread (actions/setup-python#162 (comment)), the python 3.5 and 3.6 errors might be related to the runs-on:ubuntu-latest setting, as 3.5 and 3.6 don't include files for ubuntu version 22.04 (in the list of available versions https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json).

[fgregg]

thanks!