these 2 derivations will be built:
  /nix/store/0kckhvx5hxvy7n19vl382qzafwhx9n12-nixos-test-driver-pg_cron.drv
  /nix/store/vapq4zxsyds8yq80iv8w0bbkz8vim2dp-vm-test-run-pg_cron.drv