For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:perl:CPAN-Y/openSUSE_Tumbleweed/devel:languages:perl:CPAN-Y.repo
zypper refresh
zypper install perl-YAML-Syck
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:perl:CPAN-Y/15.5/devel:languages:perl:CPAN-Y.repo
zypper refresh
zypper install perl-YAML-Syck
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/devel:languages:perl:CPAN-Y/15.4/devel:languages:perl:CPAN-Y.repo
zypper refresh
zypper install perl-YAML-Syck