CLN: str.format -> f-strings for `io/sas`
- [x] ref #29547 
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

@jyscao: Thanks for the contribution, and welcome to `pandas` !  🚀 

LGTM.  Codecov failure can be ignored.

 >     * [x]  closes #29547


Can you please change the word ```closes``` to ```ref``` ? restarted the travis build.  LGTM. Thanks @jyscao