Address lacking importlib metadata in Python ≤ 3.9

[Gallaecio]

Fixes #441.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d8d471c) 89.44% compared to head (fb8aff1) 89.44%.
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #442   +/-   ##
=======================================
  Coverage   89.44%   89.44%           
=======================================
  Files          34       34           
  Lines        2407     2407           
=======================================
  Hits         2153     2153           
  Misses        254      254           

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[Gallaecio]

The CI thing is a bit dirty, but in addition to checking for a regression on this specific issue, it also showed that we had an undeclared dependency on setuptools that would be an issue in Python 3.12.