Para 15.6 corra o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:sumaform:tools:avahi:0.8/15.6/systemsmanagement:sumaform:tools:avahi:0.8.repo
zypper refresh
zypper install libdns_sd
Para 15.5 corra o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:sumaform:tools:avahi:0.8/15.5/systemsmanagement:sumaform:tools:avahi:0.8.repo
zypper refresh
zypper install libdns_sd
Para 15.4 corra o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:sumaform:tools:avahi:0.8/15.4/systemsmanagement:sumaform:tools:avahi:0.8.repo
zypper refresh
zypper install libdns_sd