[TASK] fix php7.4 syntax issue

Author: gertvdb

lib/controller/sfRouting.class.php

@@ -299,7 +299,7 @@ public function connect($name, $route, $default = array(), $requirements = array
         $elements[count($elements) - 1] = $matches[1];
         $route = '/'.implode('/', $elements);
       }
-      else if ($route{strlen($route) - 1} == '/')
+      else if ($route[strlen($route) - 1] == '/')
       {
         $suffix = '/';
       }