formatter should change f strings using single quotes with nested double quotes to use double quotes when target-version is py312

[DetachHead]

on older python versions, the following code is a syntax error:

f"{""}"

which is why the formatter does not convert the following f string to use double quotes:

f'{""}'

but on python 3.12, it's allowed, so the formatter should always convert them to double quotes. playground

[dhruvmanila]

This is available under preview style (#9785) although it seems like the formatter still doesn't change the outer quote. For example, if the quotes are inverted (f"{''}"), the formatter changes the inner quote to use double quotes. This case (f'{""}') seems like a bug.