Add pyproject.toml

[davispuh]

This allows to easily package/install it

$ python -m build --wheel --no-isolation
$ python -m installer --destdir=$DEST dist/*.whl

There are many different build backends you can use but setuptools is well known "default" choice. You can switch to any other if you like them better etc.

See:

• https://packaging.python.org/en/latest/overview/
• https://packaging.python.org/en/latest/guides/writing-pyproject-toml
• https://build.pypa.io/en/stable/index.html

[TheFeelTrain]

I will update the PKGBUILD once this is merged