muk_base/muk_utils/data/ir_cron.xml

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

<!--     
	Copyright (C) 2017 MuK IT GmbH
	
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>. 
-->

<odoo noupdate="1">

<record id="cron_utils_update_groups" model="ir.cron">
	<field name="name">Cron job to update the Groups</field>
	<field name="active" eval="True" />
	<field name="user_id" ref="base.user_root" />
	<field name="model_id" ref="muk_utils.model_muk_utils_groups" />
	<field name="interval_number">1</field>
	<field name="interval_type">days</field>
	<field name="numbercall">-1</field>
	<field name="priority" eval="5" />
	<field name="state">code</field>
	<field name="code">
model_names = model.pool.descendants(['muk_utils.groups'], '_inherit', '_inherits')
for model_name in model_names:
  group = model.env[model_name].sudo()
  if not group._abstract:
    group.update_groups()
	</field>
</record>

</odoo>