[FIX] website_sale_digital: access rights error in preview order page

In preview order page, we are looking for product attachments, but if we are
using public user, we get an access rights error leading to a 403 page.

opw-2172563

X-original-commit: d07800eadf49e75c249f9a28aca2412b6b106793

addons/website_sale_digital/controllers/main.py

@@ -43,10 +43,10 @@ class WebsiteSaleDigital(CustomerPortal):
             # since there is nothing to pay, so we shouldn't wait for an invoice
             products = order.order_line.mapped('product_id')
 
+        Attachment = request.env['ir.attachment'].sudo()
         purchased_products_attachments = {}
         for product in products:
             # Search for product attachments
-            Attachment = request.env['ir.attachment']
             product_id = product.id
             template = product.product_tmpl_id
             att = Attachment.sudo().search_read(