Notify LimeSurvey admins when a security update is available

Ensure the LimeSurvey service admins are notified, either automatically or by the sysadmin on duty (who shall learn about this automatically), when a LimeSurvey security update is released.

Bonus points if the update has been downloaded (in a somewhat secure way) on the VM already, and is waiting for the service administrator to apply it.

Notification over email is OK, via Redmine is better if it fits in the budget.

Parent Task: #14540 (closed)

Original created by @intrigeri on 14828 (Redmine)