CLN: GH29547 replace old string formatting
Hi there! I've added some missed f-strings to:
* tests/tslibs
* tests/tseries

- [x] tests passed
- [x] passes `black pandas`

Thank you.

```
 Extension error:
Could not import extension contributors (exception: No module named 'gitdb.utils.compat')
##[error]Process completed with exit code 2.
```

We did not encounter this error during the setup, https://github.com/pandas-dev/pandas/pull/31156/checks?check_run_id=411825801. I do not have a specific idea to which this refers. @jorisvandenbossche, do you have an idea? See https://github.com/pandas-dev/pandas/issues/32060 @pcandoalmeida can you merge master and re-push? Then CI should be passing. Hi @TomAugspurger I've merged master and pushed now. Thanks! Thanks @pcandoalmeida 