gitlab-ci: move artifacts up one directory

.gitlab-ci.yml

@@ -7,9 +7,8 @@ nix:
     - nix-channel --add https://nixos.org/channels/nixos-19.03 nixpkgs
     - nix-channel --update
     - nix-build -A firmware
-    - mkdir output
-    - cp -r result/apps output/apps
+    - cp -r result/apps apps
   artifacts:
     paths:
-     - output/apps
+     - apps
     expire_in: 1 week