Apply "visibility_required" CS rule to constants

php-cs-fixer fix --rules='{"visibility_required": ["property", "method", "const"]}'

Author: nicolas-grekas

EventListener/WebDebugToolbarListener.php

@@ -35,8 +35,8 @@
  */
 class WebDebugToolbarListener implements EventSubscriberInterface
 {
-    const DISABLED = 1;
-    const ENABLED = 2;
+    public const DISABLED = 1;
+    public const ENABLED = 2;
 
     protected $twig;
     protected $urlGenerator;