it-can-be-imported-twice not testing anything

I'm not sure when this stopped testing anything. It should try to load the gitlab-ci module twice. https://gitlab.horizon-haskell.net/nix/gitlab-ci/-/blob/master/test/modules/flake/gitlab-ci/it-can-be-imported-twice/nix/ci.nix?ref_type=heads cc @smartypants @nastypants