Slack bridge: Bump slack-sdk to 3.11.2.

We also upgrade the RTM client API from v1 to v2. This is so that we no
longer require aiohttp. If we use v1, it would still require aiohttp.

zulip/integrations/bridge_with_slack/requirements.txt

@@ -1,2 +1 @@
-slack-sdk==3.5.1
-aiohttp
+slack-sdk==3.11.2

zulip/integrations/bridge_with_slack/run-slack-bridge

@@ -9,7 +9,7 @@ from typing import Any, Callable, Dict
 
 import bridge_with_slack_config
 import slack_sdk
-from slack_sdk.rtm import RTMClient
+from slack_sdk.rtm_v2 import RTMClient
 
 import zulip
 
@@ -48,7 +48,7 @@ class SlackBridge:
 
         # slack-specific
         self.channel = self.slack_config["channel"]
-        self.slack_client = RTMClient(token=self.slack_config["token"], auto_reconnect=True)
+        self.slack_client = rtm
         # Spawn a non-websocket client for getting the users
         # list and for posting messages in Slack.
         self.slack_webclient = slack_sdk.WebClient(token=self.slack_config["token"])
@@ -84,23 +84,22 @@ class SlackBridge:
     def run_slack_listener(self) -> None:
         members = self.slack_webclient.users_list()["members"]
         # See also https://api.slack.com/changelog/2017-09-the-one-about-usernames
-        self.slack_id_to_name = {
+        self.slack_id_to_name: Dict[str, str] = {
             u["id"]: u["profile"].get("display_name", u["profile"]["real_name"]) for u in members
         }
         self.slack_name_to_id = {v: k for k, v in self.slack_id_to_name.items()}
 
-        @RTMClient.run_on(event="message")
-        def slack_to_zulip(**payload: Any) -> None:
-            msg = payload["data"]
-            if msg["channel"] != self.channel:
+        @rtm.on("message")
+        def slack_to_zulip(client: RTMClient, event: Dict[str, Any]) -> None:
+            if event["channel"] != self.channel:
                 return
-            user_id = msg["user"]
+            user_id = event["user"]
             user = self.slack_id_to_name[user_id]
             from_bot = user == self.slack_config["username"]
             if from_bot:
                 return
-            self.replace_slack_id_with_name(msg)
-            content = ZULIP_MESSAGE_TEMPLATE.format(username=user, message=msg["text"])
+            self.replace_slack_id_with_name(event)
+            content = ZULIP_MESSAGE_TEMPLATE.format(username=user, message=event["text"])
             msg_data = dict(
                 type="stream", to=self.zulip_stream, subject=self.zulip_subject, content=content
             )
@@ -124,6 +123,9 @@ if __name__ == "__main__":
 
     config = bridge_with_slack_config.config
 
+    # We have to define rtm outside of SlackBridge because the rtm variable is used as a method decorator.
+    rtm = RTMClient(token=config["slack"]["token"])
+
     backoff = zulip.RandomExponentialBackoff(timeout_success_equivalent=300)
     while backoff.keep_going():
         try: