[EventHub] fix pylint (Azure#22321)

follow up fix to retry fixed mode PR: Azure#21844

Author: swathipil

sdk/eventhub/azure-eventhub/azure/eventhub/_retry.py

@@ -2,8 +2,6 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License. See License.txt in the project root for license information.
 # --------------------------------------------------------------------------------------------
-from typing import Optional, Dict, Any
-
 from enum import Enum
 
 class RetryMode(str, Enum):