add metadata

Author: taylorotwell

mail.md

@@ -1341,6 +1341,7 @@ Mail::assertSent(OrderShipped::class, function (OrderShipped $mail) use ($user)
            $mail->hasReplyTo('...') &&
            $mail->hasFrom('...') &&
            $mail->hasSubject('...') &&
+           $mail->hasMetadata('order_id', $mail->order->id);
            $mail->usesMailer('ses');
 });
 ```