Fix annotations of str methods that accept regular expressions

[hamdanal]

• Closes #xxxx (Replace xxxx with the Github issue number)
• Tests added: Please use assert_type() to assert the type of any return value

These methods accept compiled regular expressions as documented in pandas and tested at runtime.

[twoertwein]

Thank you for your well-tested PR!

These methods accept compiled regular expressions as documented in pandas

It is not clear to me if the documentation suggests that re.Pattern objects are officially accepted (for example here https://pandas.pydata.org/docs/reference/api/pandas.Series.str.extractall.html). The type is often explicitly annotated as str in pandas and the fact that not all functions accept it might hint that it is not officially accepted. I will defer to @Dr-Irv.

Feel free to open an issue/PR at pandas about it.

[Dr-Irv]

It is not clear to me if the documentation suggests that re.Pattern objects are officially accepted (for example here https://pandas.pydata.org/docs/reference/api/pandas.Series.str.extractall.html). The type is often explicitly annotated as str in pandas and the fact that not all functions accept it might hint that it is not officially accepted. I will defer to @Dr-Irv.

I think the PR discussion in pandas-dev/pandas#61879 will lead to the docs getting corrected. So I'll accept this PR as is.

[Dr-Irv]

thanks @hamdanal