Update changelog

Author: Sephster

CHANGELOG.md

@@ -5,6 +5,12 @@ 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).
 
 ## [Unreleased]
+### Added
+- Added a new function to the provided ClientTrait, `supportsGrantType` to allow the auth server to issue the response `unauthorized_client` when applicable (PR #1420)
+
+### Fixed
+- Clients only validated for Refresh, Device Code, and Password grants if the client is confidential (PR #1420)
+
 ### Changed
 - Key permission checks ignored on Windows regardless of userland choice as cannot be run successfully on this OS (PR #1447)