partner_print_voucher/static/src/xml/voucher.xml

<?xml version="1.0" encoding="UTF-8"?>
<template xml:space="preserve">
    <t t-name="partner_print_voucher.PrintVoucher">
        <button class="print_voucher oe_stat_button btn btn-default oe_inline">
            <div class="stat_button_icon fa fa-exchange"></div>
            <div>Imprimir recibo</div>
        </button>
        <!-- <ul class="oe_dropdown_menu oe_opened">
            <li class="oe_sidebar_print">
                <a class="oe_sidebar_action_a print_voucher" target="_blank" data-index="0" data-section="print">Recibo de dinero</a>
            </li>
        </ul> -->
    </t>
</template>