fix error in cronjob, fixes #3

TandemPluginCronjob.class.php

@@ -26,14 +26,6 @@ class TandemPluginCronjob extends CronJob
         return dgettext('TandemPlugin', 'Entfernt alte Tandem-Gesuche.');
     }
 
-
-    public function setUp()
-    {
-        global $STUDIP_BASE_PATH;
-        require_once($STUDIP_BASE_PATH . '/lib/classes/Config.php');
-    }
-
-
     public function execute($last_result, $parameters = [])
     {
         $delete_old_period = (int)Config::Get()->TANDEMPLUGIN_DELETE_OLD_PERIOD;