update the changelog

Author: mmomtchev

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](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [2.1.0]
+## [2.1.0] 2023-01-25
 - Builtin ultra-light heap implementation from [`heap-js`](https://github.com/ignlg/heap-js) by @ignlg
 - Drop the default export
 - Size down to 1.3KBytes when compressed