.github: Correct typo in command in issue template
.github: Correct typo in command in issue template

Use `fwupdmgr` over `fwupdgmr`.

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