Sync the php-mode.el version header with the 1.28.0 release

Author: zonuexe

lisp/php-mode.el

@@ -10,7 +10,7 @@
 ;; Maintainer: USAMI Kenta <tadsan@zonu.me>
 ;; URL: https://github.com/emacs-php/php-mode
 ;; Keywords: languages php
-;; Version: 1.26.1
+;; Version: 1.28.0
 ;; Package-Requires: ((emacs "28.1"))
 ;; License: GPL-3.0-or-later