base64ct: update changelog entry for v1.7.0 with yanked tag (#1694)

Author: newpavlov

base64ct/CHANGELOG.md

@@ -4,7 +4,7 @@ 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).
 
-## 1.7.0 (2025-02-25)
+## 1.7.0 (2025-02-25) [YANKED]
 ### Added
 - derive additional traits on alphabets ([#1578])