Update type hint in io/formats/format.py
The brackets around the type hint broke the libcst parser. Since the brackets are not necessary for the type hint, they have been removed

- [x] closes #57248
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

@twoertwein i've milestoned 3.0 since we normally don't backport typing changes and the problem code has not been modified recently but if the superfluous parenthesis breaks things feel feel to change to 2.2.1 as it would probably do no harm. Thank you @FrostMegaByte!

I'm with you, @simonjayhawkins, on not backporting (it doesn't impact major typecheckers and seems more like a libcst issue), but I have no strong opinion.