Для openSUSE Tumbleweed запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:ChristianMauderer:opensuse-installations/openSUSE_Tumbleweed/home:ChristianMauderer:opensuse-installations.repo
zypper refresh
zypper install diffpdf
Для 16.0 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:ChristianMauderer:opensuse-installations/16.0/home:ChristianMauderer:opensuse-installations.repo
zypper refresh
zypper install diffpdf
Для 15.6 запустите от имени root:
zypper addrepo https://download.opensuse.org/repositories/home:ChristianMauderer:opensuse-installations/15.6/home:ChristianMauderer:opensuse-installations.repo
zypper refresh
zypper install diffpdf