update changelog for release 4.2.1

Author: alcohol

CHANGELOG.md

@@ -7,6 +7,10 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 * Nothing as of yet
 
+## [4.2.1] - 2023-01-31
+
+* Changed: Croatia adopted the EUR on 2023-01-01
+
 ## [4.2.0] - 2023-01-23
 
 * Added: a dataprovider with often requested aliases ([#76])
@@ -70,7 +74,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 * New: initial release of `league/iso3166`.
 
-[Unreleased]: https://github.com/thephpleague/iso3166/compare/4.2.0...HEAD
+[Unreleased]: https://github.com/thephpleague/iso3166/compare/4.2.1...HEAD
+[4.2.1]: https://github.com/thephpleague/iso3166/compare/4.2.0...4.2.1
 [4.2.0]: https://github.com/thephpleague/iso3166/compare/4.1.0...4.2.0
 [4.1.0]: https://github.com/thephpleague/iso3166/compare/4.0.0...4.1.0
 [4.0.0]: https://github.com/thephpleague/iso3166/compare/3.0.0...4.0.0