Add missing "static" keyword in MD_STD

src/MD_STD.php

@@ -342,7 +342,7 @@ public static function runCurlMulti(array $urls, int $timeout = 1200):array {
      *
      * @return string
      */
-    public function get_user_lang(array $allowed_langs, string $default_lang):string {
+    public static function get_user_lang(array $allowed_langs, string $default_lang):string {
 
         $cookie_options = [
             'expires' => self::strtotime("+1 month"),