Add support for setup.cfg

[fpgmaas]

as proposed by czaki.

[fpgmaas]

Since setuptools is deprecating setup,cfg and moving towards pyproject.toml, I will close this for now.

SetuptoolsDeprecationWarning: As setuptools moves its configuration towards `pyproject.toml`,
`setuptools.config.read_configuration` became deprecated.

For the time being, you can use the `setuptools.config.setupcfg` module
to access a backward compatible API, but this module is provisional
and might be removed in the future.

[fpgmaas]

Other reasons for closing this one; AFAIK, there is no clear distinction between development and optional requirements, both can be specified under options.extras_require.