Update changelog

CHANGELOG.md

@@ -5,6 +5,13 @@ 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).
 
+## Unreleased
+
+### Fixed
+
+- Fixed the creation of the _Stripe_ checkout session for languages not supported by _Stripe_ (`ca` and `uk`)
+- Fixed the error handling in the endpoint to create a _Stripe_ checkout session
+
 ## 3.20.0 - 2026-07-04
 
 ### Changed