Added v1.2.1 to changelog

Author: acelaya

CHANGELOG.md

@@ -4,7 +4,7 @@ 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).
 
-## [Unreleased]
+## [1.2.1] - 2021-03-05
 ### Added
 * *Nothing*