[FIX] purchase: long product description

- Create a product with a very long product description
- Add in a PO and print the RFQ

The description overlaps with the table header on the second page.

This is a known issue of wkhtmltopdf (see issues 1770 and 1524 for
example), and there is no known workaround. It can be avoided by
preventing the repetition of the header.

closes odoo/odoo#114916

Opw: 3208347
X-original-commit: cc5be8a907b2c3f33c6a62c5693726d757ffd113
Signed-off-by: William Henrotin (whe) <whe@odoo.com>

addons/purchase/report/purchase_order_templates.xml

@@ -46,7 +46,7 @@
             </div>
 
             <table class="table table-sm o_main_table mt-4">
-                <thead>
+                <thead style="display: table-row-group">
                     <tr>
                         <th name="th_description"><strong>Description</strong></th>
                         <th name="th_taxes"><strong>Taxes</strong></th>