ci/eval: check that flake outputs on all systems still evaluate

        with:

          extra_nix_config: sandbox = true

      - name: Ensure flake outputs on all systems still evaluate

        run: nix --experimental-features 'nix-command flakes' flake check --all-systems --no-build

      - name: Evaluate the list of all attributes and get the systems matrix

        id: systems

        run: |