Add changelog entry

Author: Jean85

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## [Unreleased]
  - Add forward compatibility with Symfony 5 (#235, thanks to @garak)
  - Fix compatibility with sentry/sentry 2.2+ (#244)
+ - Add support for `class_serializers` option (#245)
 
 ## 3.1.0 - 2019-07-02
  - Add support for Symfony 2.8 (#233, thanks to @nocive)