Add junrar to blocklist

junrar is licensed under UnRAR license which is not an FOSS license. See also https://fedoraproject.org/wiki/Licensing:Unrar. MaterialFiles has removed junrar from F-Droid build and this change will be included in 1.5.0. When 1.5.0 is available we can disable affected versions. LiberaReader and Download Navi are also affected.