chore: Updates model_config docstring to explicitly mentioning pydantic.

This is to disambiguate between pydantic model and LLM.

PiperOrigin-RevId: 754981617

src/google/adk/events/event.py

@@ -48,6 +48,7 @@ class Event(LlmResponse):
   model_config = ConfigDict(
       extra='forbid', ser_json_bytes='base64', val_json_bytes='base64'
   )
+  """The pydantic model config."""
 
   # TODO: revert to be required after spark migration
   invocation_id: str = ''

src/google/adk/events/event_actions.py

@@ -27,6 +27,7 @@ class EventActions(BaseModel):
   """Represents the actions attached to an event."""
 
   model_config = ConfigDict(extra='forbid')
+  """The pydantic model config."""
 
   skip_summarization: Optional[bool] = None
   """If true, it won't call model to summarize function response.