Update app.py

app.py

@@ -424,7 +424,7 @@ class GaiaRunner:
             return local_path
 
         try:
-            r = _session.get(url, timeout=30)
+            r = requests.get(url, timeout=30)
             if r.status_code == 404:
                 print(f"[GAIA] No attachment found on server for task {task_id} (404).")
                 return None