Update cerebras chat example

"I'm not currently able to access real-time information. However, I can suggest some possible ways..."

Author: devmatt000

examples/cerebras/chat.php

@@ -20,7 +20,7 @@
 
 $messages = new MessageBag(
     Message::forSystem('You are a helpful assistant.'),
-    Message::ofUser('How is the weather in Tokyo today?'),
+    Message::ofUser('What is the capital of Japan?'),
 );
 $result = $platform->invoke(new Model(Model::LLAMA3_1_8B), $messages);