chore(deps): update actions/checkout action to v4 (#11)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
See: #11

.github/workflows/docker-publish.yml

@@ -36,7 +36,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       # Install the cosign tool except on PR
       # https://github.com/sigstore/cosign-installer