MNT: Condense flake8 configuration
MNT: Condense flake8 configuration

pytest-flake8 will use the flake8 section now (has for a bit now), so we
don't need to have the information duplicated in the pytest config.

Unidata/MetPy,Unidata/MetPy,ahaberlie/MetPy,dopplershift/MetPy,dopplershift/MetPy,ShawnMurd/MetPy,ahaberlie/MetPy