libmicrohttpd12 from spins:invis:15:stable:kopano project
Select Your Operating System
Add repository and install manually
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/spins:invis:15:stable:kopano/15.6/spins:invis:15:stable:kopano.repo zypper refresh zypper install libmicrohttpd12