bootstrap: Fix dnf/yum usage
bootstrap: Fix dnf/yum usage

yum is the default on fedora >= 23

GStreamer/cerbero,nirbheek/cerbero,GStreamer/cerbero,atsushieno/cerbero,nirbheek/cerbero,atsushieno/cerbero,nirbheek/cerbero,atsushieno/cerbero,GStreamer/cerbero,atsushieno/cerbero,fluendo/cerbero,fluendo/cerbero,GStreamer/cerbero,fluendo/cerbero,fluendo/cerbero,fluendo/cerbero,nirbheek/cerbero,GStreamer/cerbero,atsushieno/cerbero