Update changelog

Author: Stormheg

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.13] - UNRELEASED
 
-- Nothing new yet
+- [Drop support for Wagtail 5.2, 6.0, 6.1, and 6.2](https://github.com/wagtail-nest/wagtail-ab-testing/pull/99)
 
 ## [0.12] - 2025-04-25