Avoid invalid syntax for format-spec with quotes for all Python versions (#14625)
## Summary
fixes: #14608
The logic that was only applied for 3.12+ target version needs to be
applied for other versions as well.
## Test Plan
I've moved the existing test cases for 3.12 only to `f_string.py` so
that it's tested against the default target version.
I think we should probably enabled testing for two target version (pre
3.12 and 3.12) but it won't highlight any issue because the parser
doesn't consider this. Maybe we should enable this once we have target
version specific syntax errors in place
(https://github.com/astral-sh/ruff/issues/6591).