ci: bump actions/checkout to v5 (Node 24)

Author: markaspot

.github/workflows/docker-build.yml

@@ -24,7 +24,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
       - name: Log in to Docker Hub
         run: echo "${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}" | docker login -u "${{ secrets.DOCKER_HUB_USERNAME }}" --password-stdin