## Summary
Add new rule `pyupgrade - UP042` (I picked next available number).
Closes https://github.com/astral-sh/ruff/discussions/3867
Closes https://github.com/astral-sh/ruff/issues/9569
It should warn + provide a fix `class A(str, Enum)` -> `class
A(StrEnum)` for py311+.
## Test Plan
Added UP042.py test.
## Notes
I did not find a way to call `remove_argument` 2 times consecutively, so
the automatic fixing works only for classes that inherit exactly `str,
Enum` (regardless of the order).
I also plan to extend this rule to support IntEnum in next PR.
