these 2 derivations will be built:
  /nix/store/wrqxmzdnmagz7x84jzclr6nm3lc4zzda-nixos-test-driver-pg_cron.drv
  /nix/store/xx3wcklrn9habz93cqg8q6ipl11zl0md-vm-test-run-pg_cron.drv