chore(ruff): allow using assert in tests

This heavily simplifies type narrowing there.

Author: nijel

pyproject.toml

@@ -680,7 +680,7 @@ max-complexity = 16  # TODO: should be lower
 "fuzzing/targets.py" = ["PLC0415"]
 "scripts/*" = ["T201", "T203"]
 "weblate/*/migrations/*.py" = ["RUF012"]
-"weblate/*/tests**.py" = ["ANN001", "S105", "S106"]
+"weblate/*/tests**.py" = ["ANN001", "S101", "S105", "S106"]
 "weblate/auth/migrations/0003_fixup_teams.py" = ["T201"]
 "weblate/examples/*.py" = ["CPY001", "INP001"]
 "weblate/settings_*.py" = ["F405"]