Update prompts.yaml

prompts.yaml

@@ -320,6 +320,6 @@
     Here is the final answer from your managed agent '{{name}}':
     {{final_answer}}
 
-final_answer: |
-  This is my final answer:
-  {final_answer}
+final_answer:
+  pre_messages: |-
+    Final Answer: {final_answer}