Update changelog

CHANGELOG.md

@@ -5,6 +5,16 @@ 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).
 
+## Unreleased
+
+### Changed
+
+- Upgraded `angular-material-css-vars` from version `2.0.0` to `2.1.0`
+
+### Fixed
+
+- Fixed the warn color (button) of the theme
+
 ## 1.25.0 - 11.07.2021
 
 ### Added