Fix user map parsing for different API response formats

backup_to_hub.py

@@ -71,7 +71,12 @@ def get_user_map(headers):
         req = urllib.request.Request(f"{ARGILLA_API_URL}/api/v1/users", headers=headers)
         with urllib.request.urlopen(req, timeout=30) as resp:
             users_data = json.loads(resp.read().decode())
-        for user in users_data:
+        # Handle both list and dict (with "items" key) response formats
+        if isinstance(users_data, dict):
+            users_list = users_data.get("items", [])
+        else:
+            users_list = users_data
+        for user in users_list:
             user_map[user["id"]] = user["username"]
     except Exception as e:
         print(f"Warning: Could not fetch users: {e}", flush=True)