pandas/core/ops/: replace .format() with f-strings
- https://github.com/pandas-dev/pandas/issues/29547
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
Hello @SvoONs! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2020-03-23 17:31:46 UTC Thanks for the PR. I'm not sure we should be replacing templates. lets see what others think. Agreed with @simonjayhawkins - this is a use case where format is better than an f-string. 

Going to close since this isn't actionable, but thanks for the PR and of course would welcome contributions on other modules or issues