buildx failed with: ERROR: failed to solve: failed to push ghcr.io/collective/siteplone-backend:gdpr: unexpected status from POST request to https://ghcr.io/v2/collective/siteplone-backend/blobs/uploads/: 403 Forbidden

The following actions use a deprecated Node.js version and will be forced to run on node20: actions/setup-python@v4. For more info: https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/