flake8 config: fix typo (#8626)

Accidentally introduced in #8612

Author: AlexWaygood

.flake8

@@ -31,7 +31,7 @@ per-file-ignores =
   # https://github.com/PyCQA/flake8/issues/1079
   #     F811 redefinition of unused '...'
   stdlib/typing.pyi: E301, E302, E305, E501, E701, E741, F401, F403, F405, F811, F822, Y037
-  # Generate protobuf files include docstrings
+  # Generated protobuf files include docstrings
   *_pb2.pyi: E301, E302, E305, E501, E701, Y021, Y026
 
 exclude = .venv*,.git