ENH: Consider warnings as errors when running pytest

Consider warnings as errors when running `pytest`.

Author: jhlegarreta

tox.ini

@@ -67,7 +67,7 @@ uv_resolution =
   min: lowest-direct
 
 commands =
-  pytest --durations=20 --durations-min=1.0 --cov-report term-missing {posargs:-n auto}
+  pytest -W error --durations=20 --durations-min=1.0 --cov-report term-missing {posargs:-n auto}
 
 [testenv:style]
 description = Check our style guide