[FIX] l10n_din5008: remove border on company header

Steps to reproduce:
- Install l10n_din5008
- Go to Settings
- Configure Document Layout
- Select "DIN 5008" layout
- Download PDF Preview
An undesired solid border is displayed around the company header
in some browser like Chrome.

opw-3515961

closes odoo/odoo#136684

Signed-off-by: de Wouters de Bouchout Jean-Benoît (jbw) <jbw@odoo.com>

addons/l10n_din5008/report/din5008_report.xml

@@ -35,7 +35,7 @@
         <template id="external_layout_din5008">
             <div>
                 <div t-attf-class="header din_page o_company_#{company.id}_layout #{'din_page_pdf' if report_type == 'pdf' else ''}">
-                    <table class="company_header" t-att-style="'height: %dmm;' % (din_header_spacing or 27)">
+                    <table class="company_header table-borderless" t-att-style="'height: %dmm;' % (din_header_spacing or 27)">
                         <tr>
                             <td><h3 class="mt0" t-field="company.report_header"/></td>
                             <td><img t-if="company.logo" t-att-src="image_data_uri(company.logo)" t-att-style="'max-height: %dmm;' % (din_header_spacing or 27)"/></td>