Change way of config.php inclusion

Moodle coding style
<https://docs.moodle.org/dev/Coding_style#Require_.2F_include>
stipulates that you require (instead of require_once) config.php.

Author: Nicolas Roeser

resetprogress.php

@@ -23,7 +23,7 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
-require_once(dirname(__FILE__) . '/../../../config.php');
+require(dirname(__FILE__) . '/../../../config.php');
 require_once($CFG->dirroot .'/admin/tool/crawler/lib.php');
 require_once($CFG->libdir . '/adminlib.php');