Update docker/metadata-action digest to a64d048

Author: renovate[bot]

Diff for: .github/workflows/docker-publish.yml

@@ -64,7 +64,7 @@ jobs:
       # https://github.com/docker/metadata-action
       - name: Extract Docker metadata
         id: meta
-        uses: docker/metadata-action@f7b4ed12385588c3f9bc252f0a2b520d83b52d48
+        uses: docker/metadata-action@a64d0487d7069df33b279515d35d60fa80e2ea62
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}