Update changelog

Author: tomas-novotny

CHANGELOG.md

@@ -6,7 +6,12 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 
-## [Unreleased](https://github.com/inspirum/xml-php/compare/v3.1.0...master)
+## [Unreleased](https://github.com/inspirum/xml-php/compare/v3.1.1...master)
+
+
+## [v3.1.1 (2025-03-21)](https://github.com/inspirum/xml-php/compare/v3.1.0...v3.1.1)
+### Fixed
+- Fixed regex for element name validation
 
 
 ## [v3.1.0 (2023-11-05)](https://github.com/inspirum/xml-php/compare/v3.0.0...v3.1.0)