TYP: series apply method adds type hints

- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them

> Thanks @BeanNan for the PR. a couple of suggestions.

Corrected, please take a look see https://github.com/pandas-dev/pandas/runs/1673701200 for mypy failures CI has passed, please take a look can you merge master; your changes will now work in pandas/core/apply.py where thing were moved. Updated, but there was a slight problem with the CI that doesn't seem to be related to this commit > Updated, but there was a slight problem with the CI that doesn't seem to be related to this commit

yep, unrelated.