New failure in test_mypy

[nuclearsandwich]

Bug report

Required Info:

• Operating System:
  • All platforms
• Installation type:
  • source
• Version or commit hash:
  • 54e80d50934b3c50a7e657a1682a548700a7ddab (current HEAD of master)
• DDS implementation:
  • N/A
• Client library (if applicable):
  • N/A

Steps to reproduce issue

The last two days worth of nightlies exhibit the issue on all platforms in all configurations: e.g.

• https://ci.ros2.org/view/nightly/job/nightly_linux_release/1623/
• https://ci.ros2.org/view/nightly/job/nightly_win_deb/1699/

Additional information

Here's a relevant-seeming extract from the build log

4 errors
test\conftest.py:25:2: error: No overload variant of "fixture" matches argument type "str"
test\conftest.py:25:2: note: Possible overload variants:
test\conftest.py:25:2: note:     def [_FixtureFunction] fixture(fixture_function: _FixtureFunction, *, scope: Union[Union[Literal['session'], Literal['package'], Literal['module'], Literal['class'], Literal['function']], Callable[[str, Config], Union[Literal['session'], Literal['package'], Literal['module'], Literal['class'], Literal['function']]]] = ..., params: Optional[Iterable[object]] = ..., autouse: bool = ..., ids: Union[Iterable[Union[None, str, float, int, bool]], Callable[[Any], Optional[object]], None] = ..., name: Optional[str] = ...) -> _FixtureFunction
test\conftest.py:25:2: note:     def fixture(fixture_function: None = ..., *, scope: Union[Union[Literal['session'], Literal['package'], Literal['module'], Literal['class'], Literal['function']], Callable[[str, Config], Union[Literal['session'], Literal['package'], Literal['module'], Literal['class'], Literal['function']]]] = ..., params: Optional[Iterable[object]] = ..., autouse: bool = ..., ids: Union[Iterable[Union[None, str, float, int, bool]], Callable[[Any], Optional[object]], None] = ..., name: Optional[str] = ...) -> FixtureFunctionMarker

[nuclearsandwich]

@j-rivero FYI as requested.