inn from openSUSE:Backports:SLE-15-SP1:Update project

Select Your Operating System

For standard run the following as root:
zypper addrepo https://download.opensuse.org/repositories/openSUSE:Backports:SLE-15-SP1:Update/standard/openSUSE:Backports:SLE-15-SP1:Update.repo
zypper refresh
zypper install inn