[FEAT] Migrate setup.cfg to PEP 621

[TomJGooding]

I've always fallen back to using setup.cfg for my projects, but it's probably time to embrace PEP 621 and migrate to pyproject.toml.

Resources

• Writing your pyproject.toml
• Configuring setuptools using pyproject.toml files
• ini2toml - Automatically translates .ini/.cfg files into TOML