For SLE 12 SP3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:saltstack:products:old/SLE_12_SP3/systemsmanagement:saltstack:products:old.repo
zypper refresh
zypper install python-backports.ssl_match_hostname
For SLE 11 SP4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/systemsmanagement:saltstack:products:old/SLE_11_SP4/systemsmanagement:saltstack:products:old.repo
zypper refresh
zypper install python-backports.ssl_match_hostname