Add changelog.

Author: beauby

CHANGELOG.md

@@ -35,6 +35,7 @@ Fixes:
 - [#1358](https://github.com/rails-api/active_model_serializers/pull/1358) Handle serializer file paths with spaces (@rwstauner, @bf4)
 
 Misc:
+- [#1370](https://github.com/rails-api/active_model_serializers/pull/1370) Simplify attributes handling via a mixin (@beauby)
 - [#1233](https://github.com/rails-api/active_model_serializers/pull/1233) Top-level meta and meta_key options no longer handled at serializer level (@beauby)
 - [#1232](https://github.com/rails-api/active_model_serializers/pull/1232) fields option no longer handled at serializer level (@beauby)
 - [#1178](https://github.com/rails-api/active_model_serializers/pull/1178) env CAPTURE_STDERR=false lets devs see hard failures (@bf4)