[FIX] l10n_fr_certification: fix wrong xpath.

Bug introduced with the latest forward-port. Since the invoice's workflow has been removed in bc8d5dbf2c, the button name to cancel an invoice changed also.

addons/l10n_fr_certification/views/no_cancel.xml

@@ -15,7 +15,7 @@
             <field name="model">account.invoice</field>
             <field name="inherit_id" ref="account.invoice_form"/>
             <field name="arch" type="xml">
-                <xpath expr="//button[@name='invoice_cancel']" position="attributes">
+                <xpath expr="//button[@name='action_invoice_cancel']" position="attributes">
                     <attribute name="invisible">1</attribute>
                 </xpath>
             </field>
@@ -33,4 +33,4 @@
             </field>
         </record>
 
-</odoo>
+</odoo>