server-tools/attachment_queue/data/cron.xml

<?xml version="1.0" encoding="UTF-8"?>
<odoo noupdate="1">

    <record model="ir.cron" id="cronjob_run_attachment_queue">
        <field name='name'>Run Attachments Queue</field>
        <field name='interval_number'>30</field>
        <field name='interval_type'>minutes</field>
        <field name="numbercall">-1</field>
        <field name="active">False</field>
        <field name="doall" eval="False" />
        <field name="model_id" ref="model_attachment_queue"/>
        <field name="state">code</field>
        <field name="code">model.run_attachment_queue_scheduler()</field>
    </record>

</odoo>