Improve return type for complete_list_value (fix #132)

Author: Cito

src/graphql/execution/execute.py

@@ -760,7 +760,7 @@ def complete_list_value(
         info: GraphQLResolveInfo,
         path: Path,
         result: Iterable[Any],
-    ) -> AwaitableOrValue[Any]:
+    ) -> AwaitableOrValue[List[Any]]:
         """Complete a list value.
 
         Complete a list value by completing each item in the list with the inner type.