Update CHANGELOG for version 7.8.2

Added release notes for version 7.8.2 with fixes.

Author: funkyshu

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+## [v7.8.2] - 2025-09-16
 ### Fixed
 - Use Mockery for Azure unit tests.
 - Use more appropriate unit test assertion patterns where possible.