For SLE 15 SP3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:czanik:syslog-ng332/SLE_15_SP3/home:czanik:syslog-ng332.repo
zypper refresh
zypper install hiredis
For SLE 15 SP2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:czanik:syslog-ng332/SLE_15_SP2/home:czanik:syslog-ng332.repo
zypper refresh
zypper install hiredis
For SLE 12 SP5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:czanik:syslog-ng332/SLE_12_SP5/home:czanik:syslog-ng332.repo
zypper refresh
zypper install hiredis