http://download.opensuse.org/repositories/security:/shibboleth/CentOS_7/ is no longer working.

This is, moreover, not the project for the SP as it currently stands either.

I recommend you subscribe to the announce list where both the fact that that repository has been dead for years and has been deleted were both announced and that you follow the documentation for creating the proper Yum repository files in the RPM install section of the wiki.