Remove distutils from setup.py

[redeboer]

Thank you for developing this API package, I am following the developments with interest!

I tried to install the pdg package in Python 3.12, but get

ModuleNotFoundError: No module named 'distutils.command.register'

The reason seems to be that setup.py is using distutils has been been removed since Python 3.12:

https://github.com/particledatagroup/api/blob/ed22911000696953436ca27b32f90efeef633d7c/setup.py#L4C6-L11

This is a problem for lower versions of Python in other package managers as well, specifically when using uv.

It seems that the part that requires distutils is meant publishing the package on PyPI. This should not be exposed to the installation process. Better would be to use twine or to publish through GitHub CI.