Settings deprecation support for the docs

[flying-sheep]

Description of feature

Our deprecated isn’t integrated with our Settings docs: option: Annotated[int, Field(deprecated=...)] doesn’t result in a .. version-deprecated in the docs.

Once we have an answer in python/cpython#150076, we can change our API to just be a subclass of warnings.deprecated instead of having Deprecation, while still being able to specify version.

I’d recommend:

class deprecated(warnings.deprecated):
    __init__(
        # same as warnings.deprecated:
        self, msg: LiteralString, *, category: type[Warning] = FutureWarning, stacklevel: int = 1,
        # ours
        version: str | Version,  # still mandatory, could be renamed
        version_removed: str | Version | None = None,
    ) -> None: ...