fix: Adjusting setup.cfg to be compatible with setuptools>=78.0.0

[saboya]

This package's setup.cfg file seems to be incompatbile with the latest setuptools release:
https://setuptools.pypa.io/en/stable/history.html#v78-0-0

This is causing issues when installing project dependencies using poetry for example, as we get this error:

setuptools.errors.InvalidConfigError: Invalid dash-separated key 'description-file' in 'metadata' (setup.cfg), please use the underscore name 'description_file' instead.

[saboya]

If anyone finds this helpful, this is what helped me using poetry in a Dockerfile:

# Create a constraints file to limit setuptools version
RUN echo "setuptools<78" > /constraints.txt

# Set the PIP_CONSTRAINT environment variable to the constraints file
ENV PIP_CONSTRAINT=/constraints.txt