systemd: Make timeline.timer persistent

Without this, timeline snapshots might not be taken for up to 59
minutes after boot. This is troublesome for laptops and other use cases
where the user might not have their machine on for that long.

Author: mrkline

data/timeline.timer

@@ -5,6 +5,7 @@ Documentation=man:snapper(8) man:snapper-configs(5)
 
 [Timer]
 OnCalendar=hourly
+Persistent=true
 
 [Install]
 WantedBy=timers.target