Disable Ghost-CLI update check during ghost run

[acburdine]

Currently, Ghost-CLI runs an update check every time a command is used. This update checks pings NPM to see if a new version has been published, and if so it puts out a little notice similar to this one (image taken from the update-notifier repo):

The update-notifier package stores some basic information in ~/.config - but when ghost run is run with the ghost linux user (which doesn't have a home folder), this gets output:

┌────────────────────────────────────────

│              ghost-cli update check failed              │
│           Try running with sudo or get access           │
│          to the local update config store via           │
│ sudo chown -R $USER:$(id -gn $USER) /home/ghost/.config │
└────────────────────────────────────────

We need to disable the update check during ghost run so this message doesn't get output.