fix: improve maintenance and synchronize live conversations

backend/app/repositories/role.py

@@ -15,9 +15,9 @@ limitations under the License.
 """
 
 from sqlalchemy.orm import Session
-from typing import List, Optional, Union
+from typing import List, Optional
 from app.models.role import Role
-from app.models.permission import Permission, role_permissions
+from app.models.permission import Permission
 from app.models.user import User
 from uuid import UUID
 from app.core.logger import get_logger