Require importlib_resources for testing on Python < 3.10

[bnavigator]

Closes #7014

importlib.resources is only used in the tests. Version 5.0 is included in python 3.10+

[github-actions]

👈 Launch a Binder on branch bnavigator/notebook/importlib-resources-3.9

[bnavigator]

Now that it is testing on different Python versions, 3.12 fails on a deprecation warning which is out of the scope of this PR:

ERROR tests/test_app.py::test_notebook_handler - DeprecationWarning: datetime.utcnow() is deprecated and scheduled for removal in a future version. Use timezone-aware objects to represent datetimes in UTC: datetime.now(datetime.UTC).

[jtpio]

Should we test on all Python versions? Or maybe the lowest and highest versions (and 3.12) would be enough, like here?

notebook/.github/workflows/build.yml

Line 121 in 76db867

python: ['3.8', '3.11', '3.12']

[jtpio]

This is mostly to help reduce the number of CI jobs if they are not strictly necessary.

[bnavigator]

It's up to you, but #7014 would not have been caught by your proposed set of pythons:

There was

importlib-resources>=5.0;python_version<\"3.9\"",

and the failure was only with Python 3.9. For 3.8 we already have the backport and for python 3.10 the included stdlib is okay.

[jtpio]

Ah ok then we can keep all versions and see how it goes with CI over time.

[jtpio]

Thanks!