Para 16.0 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:Unstable/16.0/OBS:Server:Unstable.repo
zypper refresh
zypper install libarchive13
Para 15.7 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:Unstable/15.7/OBS:Server:Unstable.repo
zypper refresh
zypper install libarchive13
Para 15.6 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/OBS:Server:Unstable/15.6/OBS:Server:Unstable.repo
zypper refresh
zypper install libarchive13