[FIX] hr_luncheon_voucher: add button to existing header in employee tree view

The view inheritance was creating a duplicate <header> inside <list>

hr_luncheon_voucher/views/hr_employee_views.xml

@@ -62,15 +62,13 @@
         <field name="model">hr.employee</field>
         <field name="inherit_id" ref="hr.view_employee_tree" />
         <field name="arch" type="xml">
-            <xpath expr="//list" position="inside">
-                <header>
+            <xpath expr="//header" position="inside">
                     <button
                         type="object"
                         name="action_lv_allocations_requests_wizard"
                         string="Generate Luncheon Vouchers Allocations"
                         class="btn-primary"
                     />
-                </header>
             </xpath>
         </field>
     </record>