For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/hardware:RC-Model/openSUSE_Tumbleweed/hardware:RC-Model.repo
zypper refresh
zypper install flite
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/hardware:RC-Model/15.6/hardware:RC-Model.repo
zypper refresh
zypper install flite
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/hardware:RC-Model/15.5/hardware:RC-Model.repo
zypper refresh
zypper install flite