CI: test for file leakage
Continue troubleshooting followning #30096. 

Locally I'm seeing some failures sqlite files are leaking, but im not seeing the xls files that are causing problems in the CI.
xref https://bitbucket.org/openpyxl/openpyxl/issues/832 > I think worth adding a whatsnew as well

Sure.  Also worth questioning if we want to just bump the dependency.  I know 3.0.2 has caused some problems; if we're going to change it, might as well do it in one go. Looks like the sqlite failures are in test_memory_map and test_repr_html_ipython_config.  the test_memory_map one is fixed by running gc.collect at the end of it, but i dont have a clear fix for the ipython one.  Suggestions?

 > Can we move this cleanup to a test fixture used for the relevant tests? And just ensure that it's called for the relevant openpyxl version before check_for_file_leaks is run?

@TomAugspurger not clear on what you're asking for.  Are you looking to execute the fixture for fewer tests (to limit overhead)?  or to make the gc call in the relevant tests instead of in the library code? > or to make the gc call in the relevant tests instead of in the library code?

That. IIUC, the primary motivator here is tracing down file leaks between tests, rather than patching the behavior of old versions of openpyxl. > the primary motivator here is tracing down file leaks between tests, rather than patching the behavior of old versions of openpyxl.

I like this line of reasoning. The min version we have listed for openpyxl is 2.4.8, which was released 2017-05-30.  The earliest version that fixed this bug was 2.5.6, released 2018-08-30.  I think implementing Tom's suggestion and bumping the version (separate PR) would be reasonable here huh, putting the gc.collect in the fixture doesn't seem to get the job done.  putting it at the end of each test seems hit-and-miss.   > The min version we have listed for openpyxl is 2.4.8, which was released 2017-05-30. The earliest version that fixed this bug was 2.5.6, released 2018-08-30. I think implementing Tom's suggestion and bumping the version (separate PR) would be reasonable here

I would be +1 on just bumping and call it a day :-> thanks @jbrockmendel 

btw not sure if mention openpyxl version in install.rst, if so can you update it