[FIX] point_of_sale,sale: decorate _get_report_values with api.model

The _get_report_values method is an api.model, not an api.multi (on a purely ORM
consideration, it should have no impact on the execution on standard
code).

closes odoo/odoo#39535

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

addons/point_of_sale/models/pos_order.py

@@ -943,6 +943,7 @@ class ReportSaleDetails(models.AbstractModel):
             } for (product, price_unit, discount), qty in products_sold.items()], key=lambda l: l['product_name'])
         }
 
+    @api.model
     def _get_report_values(self, docids, data=None):
         data = dict(data or {})
         configs = self.env['pos.config'].browse(data['config_ids'])

addons/sale/report/sale_report.py

@@ -150,6 +150,7 @@ class SaleOrderReportProforma(models.AbstractModel):
     _name = 'report.sale.report_saleproforma'
     _description = 'Proforma Report'
 
+    @api.model
     def _get_report_values(self, docids, data=None):
         docs = self.env['sale.order'].browse(docids)
         return {