[FIX] website_sale: authorise the change of shipping address

Steps to reproduce:
Without being logged in,
complete the purchase flow on the ecommerce,
taking care to have a different billing
and shipping address.
If you change the delivery address,
you will get an access error.

Cause:
In some cases, we do not have access to
the `name` field of the `partner` record.

Solution:
Add `sudo` to be able to read the fields.

opw-3276877

closes odoo/odoo#122121

Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>