[Feature] Check for updates, but don't update

[assistcontrol]

📝 Provide a description of the new feature

For cronjob/automation purposes, it'd be helpful if spicetify update supported a --check argument that just checks whether a newer version is available, without committing it.

In my mind it would print a helpful message and set the exit code accordingly. That way, you also get:

if spicetify -q update --check; then [...]

➕ Additional Information

No response

[rxri]

Just use any command that does not do anything