Update changelog for 8.0.20

Author: kitchen-porter

CHANGELOG.md

@@ -5,7 +5,7 @@ This file is used to list changes made in each version of the perl cookbook.
 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).
 
-## Unreleased
+## 8.0.20 - *2025-09-04*
 
 ## 8.0.19 - *2024-11-18*