(maint) Fix 0.21.0 Changelog release version

jpogran · jpogran · commit 3980f4a813a7 · 2019-10-02T13:35:07.000-04:00
Corrects the 0.21.0 release version to the actual released version.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,7 +6,7 @@ Check [Keep a Changelog](http://keepachangelog.com/) for recommendations on how
 
 ## [Unreleased]
 
-## [0.20.0] - 2019-09-30
+## [0.21.0] - 2019-09-30
 
 ### Added
 
