fix compability

update.php

@@ -8,6 +8,11 @@
 session_start();
 include "config.php";
 
+if($db_password != null && ($db_pass == null || empty($db_pass))){
+    // compability for old version
+    $db_pass = $db_password;
+}
+
 if (empty($update_url)) {
     $update_url = 'https://github.com/hotspotbilling/phpnuxbill/archive/refs/heads/master.zip';
 }
@@ -100,7 +105,6 @@ if (empty($step)) {
     }
 } else if ($step == 4) {
     if (file_exists("system/updates.json")) {
-        require 'config.php';
         $db = new pdo(
             "mysql:host=$db_host;dbname=$db_name",
             $db_user,