fix(api): Update variable reset response to use marshal for serialization

The marshal decorator does not work properly when
the api returns a 204 response.

api/controllers/console/app/workflow_draft_variable.py

@@ -2,7 +2,7 @@ import logging
 from typing import Any, NoReturn
 
 from flask import Response
-from flask_restful import Resource, fields, inputs, marshal_with, reqparse
+from flask_restful import Resource, fields, inputs, marshal, marshal_with, reqparse
 from sqlalchemy.orm import Session
 from werkzeug.exceptions import Forbidden
 
@@ -275,7 +275,6 @@ class VariableApi(Resource):
 
 class VariableResetApi(Resource):
     @_api_prerequisite
-    @marshal_with(_WORKFLOW_DRAFT_VARIABLE_FIELDS)
     def put(self, app_model: App, variable_id: str):
         draft_var_srv = WorkflowDraftVariableService(
             session=db.session(),
@@ -298,7 +297,7 @@ class VariableResetApi(Resource):
         if resetted is None:
             return Response("", 204)
         else:
-            return variable
+            return marshal(resetted, _WORKFLOW_DRAFT_VARIABLE_FIELDS)
 
 
 def _get_variable_list(app_model: App, node_id) -> WorkflowDraftVariableList: