For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:frostik/openSUSE_Tumbleweed/home:frostik.repo
zypper refresh
zypper install bison
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:frostik/15.6/home:frostik.repo
zypper refresh
zypper install bison
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:frostik/15.5/home:frostik.repo
zypper refresh
zypper install bison
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:frostik/15.4/home:frostik.repo
zypper refresh
zypper install bison