Update app.py

app.py

@@ -75,7 +75,7 @@ def chat_with_model(message, history, context):
                 "Content-Type": "application/json"
             },
             json={
-                "model": "deepseek-ai/DeepSeek-V3.2-Exp:novita",
+                "model": "katanemo/Arch-Router-1.5B",
                 "messages": conversation
             }
         )