Bug report

Bug summary

When running tests in astropy that import matplotlib, this warning appears, causing CI to fail when we turn warnings into errors, as shown below. I also see this warning when running the tests locally (though pytest complains about it, it did not result in error during test collection 🤷‍♀ ).

astropy/conftest.py:35: in pytest_configure
    matplotlibrc_cache.update(matplotlib.rcParams)
.../matplotlib/__init__.py:886: in __getitem__
    cbook.warn_deprecated(
.../matplotlib/cbook/deprecation.py:112: in warn_deprecated
    warnings.warn(message, category, stacklevel=2)
E   matplotlib.cbook.deprecation.MatplotlibDeprecationWarning: 
E   examples.directory is deprecated; in the future, examples will be found relative to the 'datapath' directory.

Code for reproduction

See astropy/astropy#9690

Actual outcome

Traceback as described above.

Expected outcome

No warning emitted, as it was supposedly fixed in #12658 .

Matplotlib version

• Operating system: Various
• Matplotlib version: 2.x and 3.x
• Matplotlib backend (print(matplotlib.get_backend())): TkAgg (on local Windows 10 machine)
• Python version: 3.7
• Jupyter version (if applicable): N/A
• Other libraries: astropy and its test dependencies

pip installed into a conda environment (on local machine)