There are days when someone reinvents poor man's #TOML parser in setup.py to provide backwards compatibility with old #setuptools for some macOS user.

https://github.com/mk-fg/pretty-yaml/commit/1efa7da1a3a0e70bd904b6119ddd3171755732b8

#Python

pyproject: restore setup.py file because pyproject.toml doesn't seem … · mk-fg/pretty-yaml@1efa7da

…to be universally supported yet #43

GitHub

@mgorny You can use #flit to produce sdist distributions with autogenerated setup.py:

https://flit.pypa.io/en/stable/cmdline.html#cmdoption-flit-build-setup-py

#python

Flit command line interface — Flit 3.9.0 documentation

@orsinium, I know. The author apparently decided to use setuptools with PEP 621 metadata, though. Then add a compatibility shim.
@mgorny Flit also works with PEP 621 metadata. The whole point of pep was to make it possible to use different tools for the same project. It's possible to use setuptools for everything but building sdist.
@orsinium, again, I know. I just don't know why you're telling this to me rather then the package's author.