release and publish to package repo

[marc-portier]

we should assign proper release number, and get stuff up to pypi (and readthedocs)

advise and steps from:

• https://packaging.python.org/tutorials/packaging-projects/
• https://betterscientificsoftware.github.io/python-for-hpc/tutorials/python-pypi-packaging/

also - let this all be driven by a github workflow so git-release triggers all of it

additionall, if #25 has landed, then releasing up to docker-registries should be considered too