fix(core): Updated return type in 'get_obj' function

The return type of 'get_obj' function in core/service.py has been updated from StandContent[Union[Model, None]] to StandResponse. This change was made to improve readability and consistency across the application by sticking to one type of return statement.

core/service.py

@@ -123,7 +123,7 @@ def _get_obj_by_id(self, id: int, is_deleted=0) -> Union[Model, None]:
             return None
         return obj
 
-    def get_obj(self, id: int) -> StandResponse[Union[Model, None]]:
+    def get_obj(self, id: int) -> StandResponse:
         return StandResponse(data=self._get_obj_by_id(id=id))
 
     def list_obj(self, page_filter: PageFilter, page_schema: PageSchema) -> PageSchema: