Update 3.8.23 release notes with quorum queue memory fix.

(cherry picked from commit 227d319)

Author: kjnilsson

release-notes/3.8.23.md

@@ -56,6 +56,10 @@ consistent release schedule.
 
    GitHub issue: [#3409](https://github.com/rabbitmq/rabbitmq-server/pull/3409)
 
+* Quorum queues: fix memory leak when repeatedly consuming / cancelling against and empty queue.
+
+   GitHub issue: [#3445](https://github.com/rabbitmq/rabbitmq-server/issues/3445)
+
 
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