chg: [rsync-backup] launch backup 4 times a day

Signed-off-by: Valentin Lab <valentin.lab@kalysto.org>

rsync-backup/metadata.yml

@@ -13,5 +13,5 @@ uses:
     default-options:
       ## backup every day on random time
       schedule: !bash-stdout |
-        printf "%d %d * * *" "$((RANDOM % 60))" "$((RANDOM % 6))"
+        printf "%d %s * * *" "$((RANDOM % 60))" "$((RANDOM % 6))-23/6"