Fix invalid setuptools config in `setup.cfg` (will fail on `setuptools>78.0.0`)

[abravalheri]

In version 78 of setuptools, the invalid configuration in setup.cfg will start to fail (there has been a deprecation warning since 3 Mar 2021).

I also noticed that most of the information provided to setup.cfg is repeated in setup.py, so I removed the duplicated copies in setup.cfg, because the project seems to be primarily using setup.py.

Alternatively, I can also try to migrate the static configs to pyproject.toml if desired (please let me know).

[fogti]

It feels like removing stuff from setup.cfg instead of from setup.py (which could just parse the setup.cfg and get that information from there) is a mistake, simply because it removes information from simple declarative config and makes it only available via imperative config.

[abravalheri]

Alternatively, I can also try to migrate the static configs to pyproject.toml if desired (please let me know).

Fair enough, as I mentioned before, if the maintainers are interested:

Alternatively, I can also try to migrate the static configs to pyproject.toml if desired (please let me know).

In my opinion that would be best case scenario, but I don't know if there is a preference for centralising all the configs in setup.py (as it seems to be right now).