[FIX] website_sale: extra step access rights

Public users were stuck at the extra step during the checkout
process if enabled due to not having the access rights to write on
the sale.order.

addons/website_sale/controllers/main.py

@@ -101,7 +101,7 @@ class WebsiteSaleForm(WebsiteForm):
 
         order = request.website.sale_get_order()
         if data['record']:
-            order.write(data['record'])
+            order.sudo().write(data['record'])
 
         if data['custom']:
             values = {