[MRG] f-string updates for issue #29547
Addresses, in part, https://github.com/pandas-dev/pandas/issues/29547 

…ape/pivot, reshape/reshape

- [ x] xref #29547 
- [n/a ] tests added / passed
- [x ] passes `black pandas`
- [ x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [n/a ] whatsnew entry
