Move changes entry to 3.x

Signed-off-by: Jan Høydahl <jan.git@cominvent.com>

Author: janhoy

CHANGELOG.md

@@ -15,7 +15,6 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Fixed
 - Fix formatting of the main method to run for various samples ([#1749](https://github.com/opensearch-project/opensearch-java/pull/1749))
 - Fix NPE when null ObjectBuilder is accessed ([#1717](https://github.com/opensearch-project/opensearch-java/issues/1717))
-- Fixed deserialization failure when OpenSearch returns shard failures without the `primary` field in error responses by upgrading version of `opensearch-api-specification`
 
 ## [Unreleased 3.x]
 ### Added
@@ -30,6 +29,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Removed
 
 ### Fixed
+- Fixed deserialization failure when OpenSearch returns shard failures without the `primary` field in error responses by upgrading version of `opensearch-api-specification`
 
 ### Security