Removed unused use statements.

Author: Hugo Hamon

Firewall/LogoutListener.php

@@ -20,7 +20,6 @@
 use Symfony\Component\Security\Http\HttpUtils;
 use Symfony\Component\Security\Http\Logout\LogoutHandlerInterface;
 use Symfony\Component\Security\Http\Logout\LogoutSuccessHandlerInterface;
-use Symfony\Component\Security\Core\Exception\InvalidCsrfTokenException;
 
 /**
  * LogoutListener logout users.