Merge pull request #159 from bootjp/renovate/actions-checkout-6.x

Update actions/checkout action to v6

Author: bootjp

.github/workflows/docker-image.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           submodules: true