Merge pull request #23 from sapcc/renovate/actions-checkout-4.x

Update actions/checkout action to v4

.github/workflows/docker-image.yml

@@ -13,6 +13,6 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Build the Docker image
       run: docker build . --file Dockerfile --tag my-image-name:$(date +%s)