Update changelog

Author: mathbunnyru

CHANGELOG.md

@@ -3,6 +3,13 @@
 This changelog only contains breaking and/or significant changes manually introduced to this repository (using Pull Requests).
 All image manifests can be found in [the wiki](https://github.com/jupyter/docker-stacks/wiki).
 
+## 2025-03-20
+
+Affected: all images except `docker-stacks-foundation`.
+
+- **Non-breaking:** `base-notebook`: Refactor healthcheck tests to use one function ([#2254](https://github.com/jupyter/docker-stacks/pull/2254)).
+- **Non-breaking:** `base-notebook`: Test server listening on IPv4/IPv6 ([#2255](https://github.com/jupyter/docker-stacks/pull/2255)).
+
 ## 2025-03-12
 
 Affected: all images.