Use "developer" role for remaining developer-intent messages in examples

examples/foundational/55zzg-update-settings-perplexity-llm.py

@@ -63,7 +63,7 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
 
     messages = [
         {
-            "role": "user",
+            "role": "developer",
             "content": "You are a helpful assistant in a voice conversation. Your responses will be spoken aloud, so avoid emojis, bullet points, or other formatting that can't be spoken. Respond to what the user said in a creative, helpful, and brief way. Start by introducing yourself.",
         },
     ]