chore: add comment

Author: jenstroeger

.pre-commit-config.yaml

@@ -160,7 +160,9 @@ repos:
   hooks:
   - id: actionlint
 
-# On push to the remote, run the unit tests.
+# On push to the remote, run the unit tests. Note that the `COVERAGE_CORE` variable is
+# required for Python 3.12+ to make sure Coverage uses the new Python monitoring module.
+# See also: https://blog.trailofbits.com/2025/05/01/making-pypis-test-suite-81-faster/#optimizing-coverage-with-python-312s-sysmonitoring
 - repo: local
   hooks:
   - id: pytest