Try a different way of setting up nix-shell

.circleci/config.yml

@@ -145,8 +145,9 @@ jobs:
 
       - run:
           name: "Report Coverage"
-          shell: "nix-shell -p 'python.withPackages (ps: [ ps.codecov ])'"
+          shell: "nix-shell"
           command: |
+            #! nix-shell -p 'python.withPackages (ps: [ ps.codecov ])'
             cp ./result-doc/share/doc/*/.coverage ./
             python -m coverage combine
             python -m coverage report