Drop Emacs 25.1 follows php-mode.el support policy

refs emacs-php/php-mode#654

Author: zonuexe

.github/workflows/test.yml

@@ -12,7 +12,6 @@ jobs:
     strategy:
       matrix:
         emacs_version:
-        - "25.1"
         - "25.2"
         - "25.3"
         - "26.1"