Apply "visibility_required" CS rule to constants

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

Author: nicolas-grekas

WebServer.php

@@ -24,8 +24,8 @@
  */
 class WebServer
 {
-    const STARTED = 0;
-    const STOPPED = 1;
+    public const STARTED = 0;
+    public const STOPPED = 1;
 
     private $pidFileDirectory;