TST: Add test to Series.str.strip()

[minnaau]

• closes BUG: Series.str.strip() removes numeric and bool values instead of only string whitespace #44867
• tests added
• Ensure all linting tests pass, see here for how to run them
• whatsnew entry

[pep8speaks]

Hello @minnaau! Thanks for opening this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file pandas/tests/strings/test_split_partition.py:

Line 111:1: E302 expected 2 blank lines, found 1
Line 126:1: W293 blank line contains whitespace
Line 131:1: W293 blank line contains whitespace
Line 136:1: W293 blank line contains whitespace
Line 141:1: W293 blank line contains whitespace
Line 146:1: W293 blank line contains whitespace

[phofl]

What are you trying to do?

This should remove only whitespaces at the beginning or end

[simonjayhawkins]

Thanks @minnaau for the PR.

IIRC we have plenty of tests for the string methods on mixed object Series.

In the issue there is a suggestion that the docs could be updated to clarify the behavior.

So closing this PR as there is another PR open #44885 that is updating the docs and IMO we don't really need any additional tests.