Fix typing of params ids callable form

The previous typing had an object passed to the user, which they can't
do anything with without asserting, which is inconvenient. Change it to
Any instead.

Note that what comes *back* to pytest (the return value) should be an
`object`, because we want to handle arbitrary objects without assuming
anything about them.

src/_pytest/mark/structures.py

@@ -433,7 +433,7 @@ if TYPE_CHECKING:
             ids: Optional[
                 Union[
                     Iterable[Union[None, str, float, int, bool]],
-                    Callable[[object], Optional[object]],
+                    Callable[[Any], Optional[object]],
                 ]
             ] = ...,
             scope: Optional[_Scope] = ...