The connectors in this repo have been migrated to their own repositories in our new GitHub org https://github.com/splunk-soar-connectors. Please see the new org for the app you're looking for.
For more information, please see https://community.splunk.com/t5/Product-News-Announcements/SOAR-Apps-Are-Moving/ba-p/573856.