fix: wrong return type (#569)

Author: bzoracler

src/cattrs/converters.py

@@ -1214,7 +1214,7 @@ def unstructure_optional(val, _handler=handler):
 
         return unstructure_optional
 
-    def gen_structure_typeddict(self, cl: Any) -> Callable[[dict], dict]:
+    def gen_structure_typeddict(self, cl: Any) -> Callable[[dict, Any], dict]:
         """Generate a TypedDict structure function.
 
         Also apply converter-scored modifications.