Update CHANGELOG

Author: adrenth

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [3.1.0] - 2022-04-12
+
+- Add October CMS 3.x to supported versions.
+
 ## [3.0.2] - 2022-03-22
 
 - Rename migration class (duplicate class name).