Para openSUSE Leap 15.6 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:marec2000:server:messaging:dependencies/openSUSE_Leap_15.6/home:marec2000:server:messaging:dependencies.repo
zypper refresh
zypper install spdlog
Para openSUSE Leap 15.5 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:marec2000:server:messaging:dependencies/openSUSE_Leap_15.5/home:marec2000:server:messaging:dependencies.repo
zypper refresh
zypper install spdlog
Para openSUSE Leap 15.4 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/home:marec2000:server:messaging:dependencies/openSUSE_Leap_15.4/home:marec2000:server:messaging:dependencies.repo
zypper refresh
zypper install spdlog