cups-filters package was providing those packages for some time and these two packages are away for some time too, but some installations can have still those two packages installed and they aren't uninstalled without proper Obsolete:.
cups-filters-1.20.0-11.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-14b34913c8
cups-filters-1.20.0-11.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report. See https://fedoraproject.org/wiki/QA:Updates_Testing for instructions on how to install test updates. You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-14b34913c8
cups-filters-1.20.0-11.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.