trivial: Correctly search for the .cab detached signature
trivial: Correctly search for the .cab detached signature

fwupd/fwupd,hughsie/fwupd,vathpela/fwupd,hughsie/fwupd,fwupd/fwupd,hughsie/fwupd,vathpela/fwupd,superm1/fwupd,superm1/fwupd,vathpela/fwupd,fwupd/fwupd,vathpela/fwupd,fwupd/fwupd,superm1/fwupd,hughsie/fwupd