Update test/asynchronous/test_retryable_reads.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: NoahStapp

test/asynchronous/test_retryable_reads.py

@@ -22,7 +22,7 @@
 from test.asynchronous.utils import async_ensure_all_connected, async_set_fail_point
 from unittest import mock
 
-from pymongo import MongoClient, ReadPreference
+from pymongo import MongoClient
 from pymongo.common import MAX_ADAPTIVE_RETRIES
 from pymongo.errors import OperationFailure, PyMongoError