Add release notes

Author: ansd

release-notes/4.3.0.md

@@ -72,6 +72,12 @@ compared to other versions.
 
 ### Core Server
 
+#### Bug Fixes
+
+ * Quorum queue at-most-once dead lettering for the overflow behaviour `drop-head` now happens in the correct order.
+
+   GitHub issue: [#14926](https://github.com/rabbitmq/rabbitmq-server/pull/14926)
+
 #### Enhancements
 
  * When a message is rejected by a queue, RabbitMQ now provides the queue name and rejection reason to AMQP 1.0 publishers