Update CHANGELOG

Author: zonuexe

CHANGELOG.md

@@ -2,7 +2,13 @@
 
 All notable changes of the PHP Mode 1.19.1 release series are documented in this file using the [Keep a CHANGELOG](https://keepachangelog.com/) principles.
 
-<!-- ## Unreleased -->
+## Unreleased
+
+### Added
+
+ * **Support Emacs 29.1** ([#750])
+
+[#750]: https://github.com/emacs-php/php-mode/pull/750
 
 ## [1.24.3] - 2023-03-19