Update changelog

Author: rhigman

CHANGELOG.md

@@ -5,6 +5,10 @@ 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
+  - [749](https://github.com/thoth-pub/thoth/pull/749) - Correct locale code formatting in Crossref metadata output
+### Changed
+  - [749](https://github.com/thoth-pub/thoth/pull/749) - Remove ISBN limit in Crossref metadata output (introduced in v0.8.7)
 
 ## [[1.2.0]](https://github.com/thoth-pub/thoth/releases/tag/v1.2.0) - 2026-05-04
 ### Added