fix: Fixed type hinting issue with specifying Transport class (#930)

* Fixed type hinting issue with specifying Transport class

* Switching to typing.Type for compatibility with older Python versions

Author: gkevinzheng

google/cloud/logging_v2/handlers/handlers.py

@@ -18,7 +18,7 @@
 import json
 import logging
 
-from typing import Optional, IO
+from typing import Optional, IO, Type
 
 from google.cloud.logging_v2.handlers.transports import (
     BackgroundThreadTransport,
@@ -157,7 +157,7 @@ def __init__(
         client,
         *,
         name: str = DEFAULT_LOGGER_NAME,
-        transport: Transport = BackgroundThreadTransport,
+        transport: Type[Transport] = BackgroundThreadTransport,
         resource: Resource = None,
         labels: Optional[dict] = None,
         stream: Optional[IO] = None,