Resolve new flake8 error (#4462)

* Resolve flake8 error by replacing `pytest.raises(Exception)` with `SystemError`

* Also remove the obsolete comment.

* Tweak comment instead of removing it.

tests/test_modules.py

@@ -107,11 +107,10 @@ def test_def_submodule_failures():
         sm_name_orig = sm.__name__
         sm.__name__ = malformed_utf8
         try:
-            with pytest.raises(Exception):
-                # Seen with Python 3.9: SystemError: nameless module
-                # But we do not want to exercise the internals of PyModule_GetName(), which could
-                # change in future versions of Python, but a bad __name__ is very likely to cause
-                # some kind of failure indefinitely.
+            # We want to assert that a bad __name__ causes some kind of failure, although we do not want to exercise
+            # the internals of PyModule_GetName(). Currently all supported Python versions raise SystemError. If that
+            # changes in future Python versions, simply add the new expected exception types here.
+            with pytest.raises(SystemError):
                 m.def_submodule(sm, b"SubSubModuleName")
         finally:
             # Clean up to ensure nothing gets upset by a module with an invalid __name__.