web/web_decimal_numpad_dot/views/web_decimal_numpad_dot.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>

    <template id="assets_backend"
              name="numpad_dot assets" inherit_id="web.assets_backend">
        <xpath expr="." position="inside">
            <script type="text/javascript" src="/web_decimal_numpad_dot/static/src/js/numpad_dot.js"></script>
        </xpath>
    </template>

</odoo>