Switch from setup.py to pyproject.toml

[afuetterer]

The pyproject.toml file is decribed in PEP 621. It is the recommended way to package Python projects these days.

Please have a look at my fork's version of this file: https://github.com/afuetterer/BERTopic/blob/1969-toml/pyproject.toml

You are still able to do a local pip install . or pip install bertopic[gensim] from pypi.

Would you accept a PR to convert BERTopic to use pyproject.toml? Please let me know what you think.

Refs:

• https://packaging.python.org/en/latest/tutorials/packaging-projects/
• https://packaging.python.org/en/latest/guides/modernize-setup-py-project/