Remove --strict-data-files on pytest by default
- closes #22683 
Explanation:
pytest gets the configuration from setup.cfg, witch forces the option "--strict-data-files" by default. This makes the test to fail on missing files that are not packaged (on pypi and in the github tarball).
Removing this line fixes the issue and the tests are skipped.

Adding missing newline also...

Cheers.
Elias.
We want strict to be the default.

Should we instead remove setup.cfg from the distributions? > We want strict to be the default.
> 
> Should we instead remove setup.cfg from the distributions?

Assuming that the file is not being used by something else... LGTM.
Let me test without the file just in case.