TST: extern/configobj no longer excluded by pytest-dev #14930

In the weekly cron that test against dev versions of infrastructure packages, I see that it is collecting stuff that we explicitly ignored in setup.cfg like this:

Despite that directive, I see:

../../.tox/py311-test-devinfra/lib/python3.11/site-packages/astropy/extern/configobj/configobj.py F
../../.tox/py311-test-devinfra/lib/python3.11/site-packages/astropy/extern/configobj/validate.py F

Failed log: https://github.com/astropy/astropy/actions/runs/5191708098/jobs/9359883509
pytest-7.4.0.dev118+g1a175390

Last success log: https://github.com/astropy/astropy/actions/runs/5173838762/jobs/9319503854
pytest-7.4.0.dev109+ge1204e1e

I asked over at pytest-dev/pytest#11082 (comment) and hopefully this will be gone with scientific-python/pytest-doctestplus#201 🤞