Update app.py to fix gemini API issue

app.py

@@ -47,7 +47,7 @@ class BasicAgent:
                 raise ValueError("GOOGLE_API_KEY not found in environment variables")
             
             return Gemini(
-                model_name="models/gemini-pro",
+                model_name="models/gemini-1.5-flash",
                 api_key=api_key,
                 temperature=0.1,
                 top_p=0.95,