[FIX] point_of_sale: respect order date when issuing invoice

Create a sale order in POS with generate invoice option enabled.

When the user timezone is creating a day difference with respect to UTC
the date reported on the invoice will be wrong. This is caused by the
invoice date being written using `fields.Date.today()` , which is using
the UTC date. Respecting the order_date fix the issue

opw-2129440

closes odoo/odoo#41121

X-original-commit: 34fcb7300a8eb73b39f5f871e3553f036d6f3639
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/point_of_sale/models/pos_order.py

@@ -386,7 +386,7 @@ class PosOrder(models.Model):
                 # considering partner's sale pricelist's currency
                 'currency_id': order.pricelist_id.currency_id.id,
                 'invoice_user_id': order.user_id.id,
-                'invoice_date': fields.Date.today(),
+                'invoice_date': order.date_order.date(),
                 'fiscal_position_id': order.fiscal_position_id.id,
                 'invoice_line_ids': [(0, None, order._prepare_invoice_line(line)) for line in order.lines],
             }