4.1.0 release notes: update Ra version

(cherry picked from commit 22e4853)

Author: michaelklishin

release-notes/4.1.0.md

@@ -596,7 +596,7 @@ This section can be incomplete and will be expanded as 4.1 approaches its releas
 
 ### Dependency Changes
 
- * `ra` was upgraded to [`2.16.1`](https://github.com/rabbitmq/ra/releases)
+ * `ra` was upgraded to [`2.16.3`](https://github.com/rabbitmq/ra/releases)
  * `osiris` was upgraded to [`1.8.6`](https://github.com/rabbitmq/osiris/releases)
  * `observer_cli` was upgraded to [`1.8.2`](https://github.com/zhongwencool/observer_cli/releases)
  * `eetcd` was upgraded to [`0.5.0`](https://github.com/zhongwencool/eetcd/releases)