update changelog

Author: springdoc

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/spec/v2.0.0.html).
 
-## [1.2.19] - 2019-12-23
+## [1.2.20] - 2019-12-23
 
 ### Changed 
 - Preserve order of @Parameters for spring-boot 2.2 #289