Fix/attestation last attestation time race - #242

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: docker/build-push-action@v6, docker/metadata-action@v5, docker/setup-buildx-action@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Input 'install' has been deprecated with message: "docker buildx install" command is deprecated and will be removed in a future release, use BUILDX_BUILDER environment variable instead