muk_base/muk_branding/data/company.xml

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

<!--

    Copyright (c) 2017-2019 MuK IT GmbH.

    This file is part of MuK Branding 
    (see https://mukit.at).

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

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

  -->

<odoo noupdate="1">
        
    <record id="base.main_company" model="res.company">
        <field name="favicon" type="base64" file="muk_branding/static/src/img/favicon.ico"/>
    </record>

</odoo>