Exclude UP007 from Ruff Config, i.e. prefer Optional[T] over T | None

[alexjbuck]

See title. Linter rule UP007 tries to change Optional[T] into T | None and I think that the Optional[T] syntax is better. This is a residual from before Optional was possible.

The rule was originally to detect Union[T,None] and recommend T | None. I concur that T | None is better than using Union but Optional should be preferred to both. Until the linter rule is updated (there is an issue about this topic here) I recommend we add UP007 to our exclude list.

[alexjbuck]

Refer to discussion in #337. Closing issue for now. Keeping the rule enabled results in one valid way to write the type hint in question, disabling the rule results in three valid ways to write it.

T | None is the path forward until UP007 can be amended to account for Optional[T] patterns.