Update partner_compassion/models/mail_activity.py
Update partner_compassion/models/mail_activity.py

Co-authored-by: ecino <57642a6dbd5feeabed71fe929440c49c23908a9c@users.noreply.github.com>
CompassionCH/compassion-switzerland,eicher31/compassion-switzerland,eicher31/compassion-switzerland,CompassionCH/compassion-switzerland,eicher31/compassion-switzerland,CompassionCH/compassion-switzerland