Remove some unused imports

cps/kobo.py

@@ -43,7 +43,6 @@ from flask_login import current_user
 from werkzeug.datastructures import Headers
 from sqlalchemy import func
 from sqlalchemy.sql.expression import and_, or_
-from sqlalchemy.exc import OperationalError
 from sqlalchemy.orm import load_only
 from sqlalchemy.exc import StatementError
 import requests