Use Awaitable from typing module to be compatible with python 3.9-

Author: mastizada

tenacity/_asyncio.py

@@ -18,9 +18,8 @@
 import functools
 import sys
 from asyncio import sleep as aio_sleep
-from collections.abc import Awaitable
 from inspect import iscoroutinefunction
-from typing import Any, Callable, TypeVar, Union
+from typing import Any, Awaitable, Callable, TypeVar, Union
 
 from tenacity import AttemptManager, BaseRetrying, DoAttempt, DoSleep, RetryAction, RetryCallState, TryAgain