switch from setuptools to hatchling?

[mr-c]

Looks like switching to hatchling from setuptools will allow us to get rid of our hack-filled setup.py and adopt a fully modern (PEP 517/PEP 660/(PEP 621/PEP 631 pyproject.toml build configuration for cwltool, schema-salad, etc..

black switched to Hatchling last year, and they had similar mypyc, and setuptools-scm hacks: psf/black#3233

[ofek]

Maintainer of Hatchling here! Let me know if you would like me to review any PRs 🙂