Move to use pyproject.toml

[angelogladding]

https://packaging.python.org/en/latest/tutorials/packaging-projects/ revolves around pyproject.toml and makes no mention of setup.py.

We should move to pyproject.toml.

@tommorris has moved in this direction with #166 but I'd say there's a few more things to consider in the transition:

• setup.py currently imports the version number from mf2py.version
  • The Note: in the first technique listed at https://packaging.python.org/en/latest/guides/single-sourcing-package-version/ describes a variation of this for use in a pyproject.toml
• setup.py will no longer be necessary

Should we use poetry?

I only have experience with poetry. The alternatives are pip-tools and pipenv, see https://packaging.python.org/en/latest/guides/tool-recommendations/

Of those only pipenv and poetry aid you throughout the entire lifecyle of the project. I believe poetry has the better developer experience.

pipenv uses pipfile where poetry uses pyproject.toml

• poetry.lock is not typically recommended for inclusion in VCS for libraries, see https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
• requirements.txt can be auto-generated if desired, see https://python-poetry.org/docs/cli#export

[capjamesg]

This has been completed and merged into main.