apt-cacher-ng from openSUSE:Backports:SLE-15-SP1:Update project

需要 standard ，用 root 執行：

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 apt-cacher-ng