Update symfony to 3.4.11
Update symfony to 3.4.11

This resolves the following security vulnerabilities:

symfony/symfony (v3.4.4)
------------------------
 * CVE-2018-11407: CVE-2018-11407: Unauthorized access on a misconfigured LDAP server when using an empty password
   https://symfony.com/cve-2018-11407
 * CVE-2018-11386: CVE-2018-11386: Denial of service when using PDOSessionHandler
   https://symfony.com/cve-2018-11386
 * CVE-2018-11406: CVE-2018-11406: CSRF Token Fixation
   https://symfony.com/cve-2018-11406
 * CVE-2018-11408: CVE-2018-11408: Open redirect vulnerability on security handlers
   https://symfony.com/cve-2018-11408
 * CVE-2018-11385: CVE-2018-11385: Session Fixation Issue for Guard Authentication
   https://symfony.com/cve-2018-11385

SURFnet/sp-dashboard,SURFnet/sp-dashboard,SURFnet/sp-dashboard,SURFnet/sp-dashboard,SURFnet/sp-dashboard