Add GH attestations

[tazarov]

https://github.com/actions/attest-build-provenance?tab=readme-ov-file#container-image

- name: Attest
        uses: actions/attest-build-provenance@v2
        id: attest
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          subject-digest: ${{ steps.build-and-push.outputs.digest }}
          push-to-registry: true

Important

What should be the subject hame here? We have multiple tags for tag in $(echo '${{ steps.meta.outputs.tags }}' | grep '^ghcr.io'); do