add changelog entry

Signed-off-by: Onur Özkan <work@onurozkan.dev>

Author: onur-ozkan

protocols/gossipsub/CHANGELOG.md

@@ -19,13 +19,16 @@
 
 - Fix incorrect default values in ConfigBuilder
   See [PR 6113](https://github.com/libp2p/rust-libp2p/pull/6113)
-  
+
 - Remove duplicated config `set_topic_max_transmit_size` method, prefer `max_transmit_size_for_topic`.
   See [PR 6173](https://github.com/libp2p/rust-libp2p/pull/6173).
 
 - Switch the internal `async-channel` used to dispatch messages from `NetworkBehaviour` to the `ConnectionHandler`
   with an internal priority queue. See [PR 6175](https://github.com/libp2p/rust-libp2p/pull/6175)
 
+- Refactor gossipsub with in-place negative-score peer removal.
+  See [PR 6209](https://github.com/libp2p/rust-libp2p/pull/6209).
+
 ## 0.49.2
 
 - Relax `Behaviour::with_metrics` requirements, do not require DataTransform and TopicSubscriptionFilter to also impl Default