Add build and publish workflow

[itrharrison]

To avoid the current situation:
where the version on PyPI is v0.2 but because the build and publish happened offline, the version information is out of sync with what is in setup.py

this PR automates the build and publish to PyPI process.

The workflow would be (on the github repo)

• "Create a new release"
• Create a new tag corresponding to the new version number
• Hit "Publish release"

this will then trigger a github action which builds the package and uploads it to PyPI with the corresponding version number.

Someone would need to create the project on PyPI first. Happy to go through this with someone in person and then convert this PR from draft when we're ready.

[mgerbino]

Hello @itrharrison, is this still valid? Happy to go through it together and close it, in case.

[itrharrison]

I think having a build and publish workflow would still be useful! Like I said above, just needs someone (could be me) to set things up on PyPI