Update CHANGELOG.md

Author: vfalies

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [1.2.1] - 2018-06-10
+
+### Changed
+
+- Update squizlabs/php_codesniffer in / from 3.2.3 to 3.3.0
+
 ## [1.2.1] - 2018-03-07
 
 ### Changed