modem-manager: explicitly use plain version format
modem-manager: explicitly use plain version format

The devices managed by this plugin expose version strings that are to
be treated as plain ASCII and compared just as plain ASCII.

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