Update actions/checkout action to v4

.github/workflows/docker-publish.yml

@@ -20,7 +20,7 @@ jobs:
     if: github.event_name == 'push'
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Build image
         run: docker build . --file Dockerfile --tag $IMAGE_NAME --cache-from ghcr.io/${{ github.repository }}:latest