chore(deps): update actions/checkout action to v5 (#6671)

Signed-off-by: milkmaker <milkmaker@mailcow.de>
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

.github/workflows/rebuild_backup_image.yml

@@ -13,7 +13,7 @@ jobs:
       packages: write
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v5
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3