[CLN] remove now-unnecessary td.skip_if_no(pathlib)
- [ ] closes #30375 
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

@simonjayhawkins sure, done - thanks for your review, and sorry for not having picked up on that straight away thanks @MarcoGorelli 