For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Skirmisher:branches:Linux-PAM/openSUSE_Tumbleweed/home:Skirmisher:branches:Linux-PAM.repo
zypper refresh
zypper install pam_ssh_agent_auth
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Skirmisher:branches:Linux-PAM/15.5/home:Skirmisher:branches:Linux-PAM.repo
zypper refresh
zypper install pam_ssh_agent_auth
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:Skirmisher:branches:Linux-PAM/15.4/home:Skirmisher:branches:Linux-PAM.repo
zypper refresh
zypper install pam_ssh_agent_auth