[FIX] website_sale: avoid subscribing the website user (Public) to all shop orders

Especially as this user does not have a valid email, which
could prevent notifications to reach other followers.

addons/website_sale/controllers/main.py

@@ -526,7 +526,7 @@ class website_sale(http.Controller):
 
         order_info = {
             'partner_id': partner_id,
-            'message_follower_ids': [(4, partner_id)],
+            'message_follower_ids': [(4, partner_id), (3, request.website.partner_id.id)],
             'partner_invoice_id': partner_id,
         }
         order_info.update(order_obj.onchange_partner_id(cr, SUPERUSER_ID, [], partner_id, context=context)['value'])