Publish to PyPI workflow

[ethansocal]

As suggested in the code review from Python Discord, it would be beneficial to have a Github Actions workflow that publishes the package to PyPI on commits to main, or tagged commits.

[doublevcodes]

I would be willing to set this up.

[ethansocal]

@doublevcodes That would be great! I'll assign you

[briancohan]

@doublevcodes, If it's not too much for this issue, I'd like to see this improve tox.ini so that it runs pytest on 3.7, 3.8, 3.9, and 3.10dev and add documentation, possibly to CONTRIBUTING.md on how to run the tests with tox locally.

Either way, we appreciate the help!

[doublevcodes]

That seems totally fine, I'll figure that out and ask about for any questions.

[VagishVela]

@doublevcodes How is it coming along? Do you need any help?