Correct duplicated changelog header (opensearch-project#517)

Signed-off-by: Thomas Farr <[email protected]>

CHANGELOG.md

@@ -12,12 +12,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ### Fixed
 - Fix `HttpConnection.ConvertHttpMethod` to support `Patch` method ([#489](https://github.com/opensearch-project/opensearch-net/pull/489))
-
-
-### Fixed
 - Fixed `IEnumerable<int?>` property mapping. ([#503](https://github.com/opensearch-project/opensearch-net/pull/503))
 
-
 ### Dependencies
 - Bumps `Microsoft.CodeAnalysis.CSharp` from 4.2.0 to 4.6.0
 - Bumps `NSwag.Core.Yaml` from 13.19.0 to 13.20.0
@@ -145,4 +141,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 [1.6.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.5.0...v1.6.0
 [1.5.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.4.0...v1.5.0
 [1.4.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.3.0...v1.4.0
-[1.3.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.2.0...v1.3.0
+[1.3.0]: https://github.com/opensearch-project/opensearch-net/compare/v1.2.0...v1.3.0