social/mail_activity_team/models/res_users.py

# Copyright 2018 Eficent Business and IT Consulting Services, S.L.
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
from odoo import models, fields


class ResUsers(models.Model):
    _inherit = "res.users"

    activity_team_ids = fields.Many2many('mail.activity.team',
                                         'mail_activity_team_users_rel',
                                         string="Activity Teams")