fix missing quotes

Author: mme

typescript-sdk/integrations/langgraph/python/ag_ui_langgraph/examples/agents/human_in_the_loop.py

@@ -30,6 +30,7 @@ def plan_execution_steps(
     """
     Make up 10 steps (only a couple of words per step) that are required for a task. 
     The step should be in imperative form (i.e. Dig hole, Open door, ...).
+    """
 
 class AgentState(MessagesState):
     """