Release 0.21.0

Author: aomarks

CHANGELOG.md

@@ -4,7 +4,9 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## Unreleased
+<!-- ## Unreleased -->
+
+## [v0.22.0] - 2021-07-14
 
 ### Changed
 - all