fix(core): Reorder field_validator and classmethod to fit Pydantic V2. (#5257)

api/core/app/entities/queue_entities.py

@@ -77,8 +77,8 @@ class QueueIterationNextEvent(AppQueueEvent):
     node_run_index: int
     output: Optional[Any] = None # output for the current iteration
 
-    @classmethod
     @field_validator('output', mode='before')
+    @classmethod
     def set_output(cls, v):
         """
         Set output