Notify users of Raspberry Pi 5 power issues via update-motd

 pemmican is a trivial service which notifies users of issues reported by the
 Raspberry Pi 5 PMIC (Power Management IC). Specifically, reset due to
 undervolt, runtime undervolt, overcurrent in USB peripherals, and failure to
 negotiate a 5A supply are all reportable issues.
 .
 This package installs the man:update-motd(5) hook to run man:pemmican-cli(1)
 on server installations.