For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:eroca:gitea/openSUSE_Tumbleweed/home:eroca:gitea.repo
zypper refresh
zypper install gitea
For 16.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:eroca:gitea/16.0/home:eroca:gitea.repo
zypper refresh
zypper install gitea
For 15.7 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:eroca:gitea/15.7/home:eroca:gitea.repo
zypper refresh
zypper install gitea