Transition setup.py to pyproject.toml and other software tools to potentially replace tox

[mxochicale]

I am raising this one to transition from setup.py to pyproject.toml. This is in line with the PEP 621, where the Python community selected pyproject.toml as a standard way of specifying project metadata. Similarly, in this issue we can track better software practices to improve testing experience with python standards (e.g. nox, Invoke, etc).

Investigate GitHub actions for nox, invoke

• https://github.com/marketplace/actions/setup-nox
• can we use tox with conda?

References

https://pybit.es/articles/how-to-package-and-deploy-cli-apps/