[FIX] pos_daily_sales_reports: key not correct

The key chosed in the SaleDetailsReport.xml file following
t-foreach instructions were not properly chosen. When 2 products were
bought but with different price or different discount, the key
was the same leading to an error. This fix aims at resolving
this problem.

closes odoo/odoo#119026

Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>

addons/pos_daily_sales_reports/static/src/xml/SaleDetailsReport.xml

@@ -9,7 +9,7 @@
     
             <div class="orderlines">
                 <t t-foreach="products" t-as="category" t-key="category['name']">
-                    <t t-foreach="category['products']" t-as="line" t-key="line['product_id']">
+                    <t t-foreach="category['products']" t-as="line" t-key="line_index">
                         <div class="responsive-price">
                             <t t-esc="line['product_name'].substr(0,20)" />
                             <span class="pos-receipt-right-align">
@@ -38,7 +38,7 @@
     
             <div class="orderlines">
                 <t t-foreach="refund_products" t-as="category" t-key="category['name']">
-                    <t t-foreach="category['products']" t-as="line" t-key="line['product_id']">
+                    <t t-foreach="category['products']" t-as="line" t-key="line_index">
                         <div class="responsive-price">
                             <t t-esc="line['product_name'].substr(0,20)" />
                             <span class="pos-receipt-right-align">