Add PHP-8.5 to the Git steps page

Author: DanielEScherzer

git.php

@@ -102,6 +102,9 @@
   <strong>PHP HEAD</strong>:
   <code>git checkout master</code>
   <br>
+  <strong>PHP 8.5</strong>:
+  <code>git checkout PHP-8.5</code>
+  <br>
   <strong>PHP 8.4</strong>:
   <code>git checkout PHP-8.4</code>
   <br>