Bug#948980: schleuder: notification mails sent to admins are missing List-Id header

[Georg Faerber]

Package: schleuder
Version: 3.4.1-1
Forwarded: https://0xacab.org/schleuder/schleuder/merge_requests/312

Notification mails sent to admins do not include a List-Id header, which
makes sorting such mails unnecessary hard.