chore(docker): enable sbom and cache

Update the Docker publishing Action to enable SBOM and provenance
attestations to the published images, as well as enabling caching of
layers across runs.

.github/workflows/docker.yaml

@@ -25,5 +25,9 @@ jobs:
         with:
           file: ./cmd/controller/Dockerfile
           platforms: linux/amd64, linux/arm64
+          sbom: true
           tags: ${{ steps.docker-meta.outputs.tags }}
+          labels: ${{ steps.docker-meta.outputs.labels }}
           push: ${{ startsWith(github.ref, 'refs/tags/v') }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max