Para 15.5 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:Kolab:16.1/15.5/server:Kolab:16.1.repo
zypper refresh
zypper install libjansson
Para 15.4 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:Kolab:16.1/15.4/server:Kolab:16.1.repo
zypper refresh
zypper install libjansson
Para 15.3 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:Kolab:16.1/15.3/server:Kolab:16.1.repo
zypper refresh
zypper install libjansson