Update CHANGELOG.

CHANGELOG.md

@@ -6,6 +6,11 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+## [4.0.1] 2019-10-08
+### Fixed
+  * [#552](https://github.com/jhedstrom/drupalextension/issue/552) Remove hard-coded symfony/event-dispatcher requirement.
+### Changed
+  * [#553](https://github.com/jhedstrom/drupalextension/pull/553) Remove testing on PHP 5.6 and Drupal 6
 ## [4.0.0] 2019-09-27
 ## [4.0.0 rc1] 2019-07-24
 ### Changed
@@ -108,7 +113,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   * [#437](https://github.com/jhedstrom/drupalextension/pull/437): Radio button selector fix.
   * [#439](https://github.com/jhedstrom/drupalextension/pull/439): Symfony 3 compatibility follow-up fix.
 
-[Unreleased]: https://github.com/jhedstrom/drupalextension/compare/v4.0.0...HEAD
+[Unreleased]: https://github.com/jhedstrom/drupalextension/compare/v4.0.1...HEAD
+[4.0.1]: https://github.com/jhedstrom/drupalextension/compare/v4.0.0...v4.0.1
 [4.0.0]: https://github.com/jhedstrom/drupalextension/compare/v4.0.0rc1...v4.0.0
 [4.0.0 rc1]: https://github.com/jhedstrom/drupalextension/compare/v4.0.0beta2...v4.0.0rc1
 [4.0.0 beta2]: https://github.com/jhedstrom/drupalextension/compare/v4.0.0beta1...v4.0.0beta2