[-] INSTALLER: Fix syntax error, unexpected 'public' (T_PUBLIC)

install-dev/upgrade/php/update_customer_default_group.php

@@ -24,7 +24,7 @@
 *  International Registered Trademark & Property of PrestaShop SA
 */
 
-public function update_customer_default_group()
+function update_customer_default_group()
 {
 	$filename = _PS_ROOT_DIR_.'/config/defines.inc.php';
 	$filename_old = str_replace('.inc.', '.old.', $filename);