Remove old docstring note

src/fastmcp/utilities/types.py

@@ -35,9 +35,6 @@ def get_cached_typeadapter(cls: T) -> TypeAdapter[T]:
     create them once in a global scope and reuse them as often as possible.
     However, this isn't feasible for user-generated functions. Instead, we use a
     cache to minimize the cost of creating them as much as possible.
-
-    The _parent_depth is set to 3 to look at an additional frame, since this
-    function is in its own scope.
     """
     return TypeAdapter(cls)