Update src/fastapi_oauth2/middleware.py

Co-authored-by: Artyom Vancyan <44609997+ArtyomVancyan@users.noreply.github.com>

Author: Scurrra

src/fastapi_oauth2/middleware.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 from datetime import timedelta
-from datetime import UTC
+from datetime import timezone
 from typing import Any
 from typing import Awaitable
 from typing import Callable