• Follow-up from drop pkg_resources in favour of importlib.metadata #5923

Now that we no longer use pkg_resources, can we drop the run-time dependency from setuptools altogether?

I see it used:

• in setup.py (which is not runtime)
• in versioneer.py, with a fallback to distutils if it's not already loaded. Unsure about the implications of this.
• in a single test (test_upload_file_egg) which could have pytest.importorskip

Notably, setuptools is already not in requirements.txt. However, I can see it in the conda recipe:

run:
    [...]
    - setuptools <60.0.0

Not sure why? xref #5802 where it was added.

CC @graingert @charlesbluca