i am using below code..below code migrated from v10 to v13
<template id="template" xml:space="preserve">
<t t-extend="ListView.buttons" t-name="customListView.buttons">
<t t-jquery="button.o_list_button_add" t-operation="before">
<!-- Sale Unit -->
<!-- -->
<button t-if="widget.modelName == 'account.asset.asset' and widget.options.action['xml_id'] == 'bi_property_management_extend.action_property_assets_view_from_sale'"
class="btn btn-primary btn-sm oe_action_buttons addMore"
style="width:50px;" type="button">
<span class="fa fa-search-plus" title="Advance Search Sale Unit"/>
</button>
<button t-if="widget.modelName == 'account.asset.asset' and widget.options.action['xml_id'] == 'bi_property_management_extend.action_property_assets_view_from_sale'"
class="btn btn-primary btn-sm oe_action_refresh_buttons"
type="button"><span class="fa fa-refresh" style="font-size:18px" title="Refresh"/></button>
</t>
</t>
</template>