Mark release

Author: pmlopes

CHANGELOG.md

@@ -5,7 +5,7 @@ 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).
 
-## [0.21.0] -
+## [0.21.0] - 2023-12-18
 * Bumped Graal to 23.0.2
 * Bumped vertx to 4.5.1
 * Bumped Graal to 23.0.1