Update changelog for 8.2.0 release

Author: EvanHahn

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-## Unreleased
+## 8.2.0 - 2026-05-21
 
 - `Cross-Origin-Opener-Policy`: support `noopener-allow-popups`. See [#522](https://github.com/helmetjs/helmet/pull/522)
 - Improve error message when passing duplicate options