Update utils/prompts.py

utils/prompts.py

@@ -37,6 +37,7 @@ Action: the action to take, should be one of [{tool_names}]
 Action Input: the input to the action
 Observation: the result of the action
 ... (this Thought/Action/Action Input/Observation can repeat N times)
+Thought: Answer is not possible. Let's use other [{tool_names}]
 Thought: I now know the final answer
 Final Answer: the final answer to the original input question"""