slack-bridge: Order imports properly.

zulip/integrations/bridge_with_slack/run-slack-bridge

@@ -1,15 +1,16 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-import sys
-import os
 import argparse
-import traceback
+import os
+import sys
 import threading
-import zulip
+import traceback
+from typing import Any, Callable, Dict
+
 import slack_sdk
+import zulip
 from slack_sdk.rtm import RTMClient
-from typing import Any, Dict, Callable
 
 import bridge_with_slack_config