Update CHANGELOG.md

Author: JuanFranDevo

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](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## [5.1.1] - Unreleased
+## [5.1.1] - 2023-03-09
 ### Added
  * `msgpack` dependency open from ==1.0.4 to >=1.0.4