ruff

f7802ad5 - [`pylint`] Extend docs and test in `invalid-str-return-type` (`E307`) (#10400)

[`pylint`] Extend docs and test in `invalid-str-return-type` (`E307`) (#10400) ## Summary Added some docs, and a little of test cases in `invalid-str-return-type`, mentioned in https://github.com/astral-sh/ruff/pull/10377#pullrequestreview-1934295027 ## Test Plan On `invalid_return_type_str.py`. --------- Co-authored-by: Dhruv Manilawala <dhruvmanila@gmail.com>