Update app.py

app.py

@@ -31,7 +31,7 @@ MODELS = {
     },
     "Mistral Small": {
         "api_url": "https://openrouter.ai/api/v1/chat/completions",
-        "model": "mistralai/mistral-small-3.1-24b-instruct:free",
+        "model": "mistralai/ministral-8b",
         "key_env": "OPENROUTER_API_KEY",
         "response_format": {"type": "json_object"},
         "extra_headers": {