docs: match async setups in testing

Author: zimeg

scripts/codegen.py

@@ -54,6 +54,11 @@
     )
     async_source = re.sub(r"ChatStream:", "AsyncChatStream:", async_source)
     async_source = re.sub(r"ChatStream\(", "AsyncChatStream(", async_source)
+    async_source = re.sub(
+        r" client.chat_stream\(",
+        " await client.chat_stream(",
+        async_source,
+    )
     async_source = re.sub(
         r" streamer.append\(",
         " await streamer.append(",

slack_sdk/web/async_client.py

@@ -2939,7 +2939,7 @@ async def chat_stream(
 
         Example:
             ```python
-            streamer = client.chat_stream(
+            streamer = await client.chat_stream(
                 channel="C0123456789",
                 thread_ts="1700000001.123456",
                 recipient_team_id="T0123456789",