trivial: Be more explicit when building on Centos
trivial: Be more explicit when building on Centos

Newer versions of appstream-glib do not depend on libgcab and so it has to be
installed manually to ensure the CI still passes.

hughsie/fwupd,hughsie/fwupd,vathpela/fwupd,vathpela/fwupd,vathpela/fwupd,fwupd/fwupd,fwupd/fwupd,vathpela/fwupd,fwupd/fwupd,fwupd/fwupd,hughsie/fwupd,hughsie/fwupd