Updated CHANGELOG

Author: Surfoo

CHANGELOG.md

@@ -4,6 +4,10 @@ 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).
 
+## [3.20.0] - 2023-04-27
+### Added
+    - isReferenceCode() and isGeocode() methods
+
 ## [3.19.0] - 2023-02-09
 ### Added
     - Compatibility with PHP 8.2 and monolog 3.0