modernize packaging using pyproject.toml

[dulmandakh]

Description of the Change

This PR modernizes packaging using pyproject.toml instead of setup.py. See https://packaging.python.org/en/latest/guides/modernize-setup-py-project/

You can test the change using below command

tox -e build

Checklist

• PR only contains one change (considered splitting up PR)
• unit-test added
• documentation updated
• CHANGELOG.md updated (only for user relevant changes)
• author name in AUTHORS

[n2ygk]

We need to think hard about this since the package builds and twine uploads to pypi are somehow automated by jazzband magic.

[dulmandakh]

python -m build output artifact is same with python setup.py sdist --format=gztar bdist_wheel, thus twine check works as expected. IMHO, there won't be any change in package publishing, please see https://packaging.python.org/en/latest/guides/distributing-packages-using-setuptools/.

[n2ygk]

Let's give it a shot. We'll find out soon enough if there's issues with Jazzband's scripts that push to pypi.