GitLab

This allows building packages after the tag was pushed but before the corresponding GitHub release was published.

The same change was already done in deb-icinga2:
deb-icinga2@e8e9e552

Add bullseye

See merge request !8

Release 2.13.1-1

See merge request !6

Note: The release builds for this security update were prepared in a private
fork before publishing the release and were uploaded from there:
https://git.icinga.com/packaging/icinga-2-security-releases-2.13.1-2.12.6-2.11.11/raspbian-icinga2

[ci skip]

This will ease dependency installation on Raspbian, where aptitude can
not be used (pbuilder-satisfydepends-aptitude).

Make stretch the default version

[ci skip]

chown several files and directories to the daemon user.