feat: Keep last 5 snapshots in restic retention policy

Author: RogueOneEcho

README.md

@@ -28,7 +28,7 @@ Docker container for backing up service data to Backblaze B2 using rsync and res
 ```yaml
 services:
   backup-myservice:
-    image: ghcr.io/rogueoneecho/backup:latest
+    image: ghcr.io/rogueoneecho/backup
     userns_mode: host
     environment:
       NAME: myservice

src/backup

@@ -333,6 +333,7 @@ restic-forget () {
   start-timer
   if restic forget \
       --repo "${RESTIC_REPO}" \
+      --keep-last 5 \
       --keep-daily 7 \
       --keep-weekly 4 \
       --keep-monthly 12 \