CLN:F-string in pandas/_libs/tslibs/*.pyx
- [ ] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

ref https://github.com/pandas-dev/pandas/issues/29547
thanks @MomIsBestFriend 