pythonPackages.pytest-services: make it build with darwin sandbox

pkgs/development/python-modules/pytest-services/default.nix

···
     "test_xvfb"
   ];
 
+  # Tests use sockets
+  __darwinAllowLocalNetworking = true;
+
   meta = with lib; {
     description = "Services plugin for pytest testing framework";
     homepage = "https://github.com/pytest-dev/pytest-services";