nbstripout: moving buildInputs to checkInputs

Fixes https://hydra.nixos.org/build/98602011

pkgs/applications/version-management/nbstripout/default.nix

@@ -9,7 +9,8 @@ buildPythonApplication rec {
   # Mercurial should be added as a build input but because it's a Python
   # application, it would mess up the Python environment. Thus, don't add it
   # here, instead add it to PATH when running unit tests
-  buildInputs = [ pytest pytest-flake8 pytest-cram git pytestrunner ];
+  checkInputs = [ pytest pytest-flake8 pytest-cram git ];
+  nativeBuildInputs = [ pytestrunner ];
   propagatedBuildInputs = [ ipython nbformat ];
 
   # PyPI source is currently missing tests. Thus, use GitHub instead.