CHANGELOG: update

Signed-off-by: Gyuho Lee <[email protected]>

Author: gyuho

CHANGELOG/CHANGELOG-1.5.md

@@ -2,7 +2,7 @@
 
 <hr>
 
-## [v1.5.9](https://github.com/aws/aws-k8s-tester/releases/tag/v1.5.9) (2021-04)
+## [v1.5.9](https://github.com/aws/aws-k8s-tester/releases/tag/v1.5.9) (2021-04-26)
 
 ### `client`