fix: update stream_chat/async_chat/channel.py

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: totalimmersion

stream_chat/async_chat/channel.py

@@ -213,12 +213,8 @@ async def unmute(self, user_id: str) -> StreamResponse:
     async def pin(self, user_id: str) -> StreamResponse:
         if not user_id:
             raise StreamChannelException("user_id must not be empty")
-        
-        payload = {
-            "set": {
-                "pinned": True
-            }
-        }
+
+        payload = {"set": {"pinned": True}}
         return self.client.patch(f"{self.url}/member/{user_id}", data=payload)
 
     async def unpin(self, user_id: str) -> StreamResponse: