Packaging should be updated to `pyproject.toml`

[sfluegel05]

This is not an urgent issue since our installation process is working fine with pip, but it is officially recommended to add a pyproject.toml instead of just a setup.py.

Todo

• Check what the standards for a modern python repository are - a good starting point is this User Guide
• Check to which extend we don't fulfill those standards
• Update our repository to meet the standards

[aditya0by0]

Installing collected packages: chebai
  DEPRECATION: Legacy editable install of chebai==1.0.0 from file:///G:/github-aditya0by0/python-chebai (setup.py develop) is deprecated. pip 25.1 will enforce this behaviour change. A possible replacement is to add a pyproject.toml or enable --use-pep517, and use setuptools >= 64. If the resulting installation is not behaving as expected, try using --config-settings editable_mode=compat. Please consult the setuptools documentation for more information. Discussion can be found at https://github.com/pypa/pip/issues/11457
  Running setup.py develop for chebai
Successfully installed chebai

[aditya0by0]

https://packaging.python.org/en/latest/guides/writing-pyproject-toml/