Convert setup.py to pyproject.toml

[hugovk]

Fixes #4.

I used two tools for this:

• https://github.com/gvalkov/setuptools-py2cfg
• https://github.com/abravalheri/ini2toml

I used the first to convert setup.py to setup.cfg, and the second from setup.cfg to pyproject.toml, something like this:

pip install setuptools-py2cfg ini2toml
setuptools-py2cfg setup.py > setup.cfg
ini2toml setup.cfg > pyproject.toml
rm setup.*

Next, I added a few more pre-commit hooks, one to format pyproject.toml to make it easy to compare against other projects, and some others to check TOML and YAML files.

Then to check the output is okay, I ran:

pip install build
python -m build

Which creates an sdist and wheel in the dist directory. I compared the output from master and from this branch, and there were no unexpected differences.

We're still using setuptools here as the "build backend", which is just fine. We can also easily change it to others too. I tend to use hatchling, but it doesn't make too much difference.

[egeakman]

Thanks Hugo!