chore(gitlab-ci): fix syntax contd

.gitlab-ci.yml

@@ -92,7 +92,7 @@ backend dependencies:
         - .stack
         - .stack-work
   script:
-    - "nix shell .#gnumake .#stack .#coreutils --command sh -c 'prepare-env && make backend-dependencies'" # TODO maybe remove prepare-env
+    - "nix shell .#gnumake .#stack .#coreutils .#prepareEnv --command sh -c 'prepare-env && make backend-dependencies'" # TODO maybe remove prepare-env
     - "ls -a ." # TODO: debug only
     - "ls -a ${HOME}/.stack"
   before_script: *nix-before

shell.nix

@@ -264,7 +264,7 @@ let
   '';
 
   prepareEnv = pkgs.writeScriptBin "prepare-env" ''
-    #!${pkgs.zsh}/bin/zsh
+    #!/bin/sh
 
     export TZDIR=${pkgs.tzdata}/share/zoneinfo
     export CHROME_BIN=${pkgs.chromium}/bin/chromium