Update changelog

CHANGELOG.md

@@ -4,10 +4,11 @@ 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).
 
-## 0.6.4 - 2020-07-27
+## 0.6.5 - 2020-08-10
 ### Added
 - Added support for fetching multiple header values. https://github.com/uber/zanzibar/pull/733.
 - Set explicit import alias for github.com/uber/zanzibar/runtime in templates. https://github.com/uber/zanzibar/pull/734.
+- Added support for multiple header values in TestGateway utility. https://github.com/uber/zanzibar/pull/737.
 
 ## 0.6.2 - 2020-07-17
 ### Added