python3Packages.setproctitle: fix darwin build

Some tests got re-enabled in https://github.com/NixOS/nixpkgs/pull/444696, but one of them fails on Darwin: https://github.com/dvarrazzo/py-setproctitle/blob/master/tests/setproctitle_test.py#L73C5-L73C29

I couldn't figure out the root cause, maybe it has to do with the Nix builder environment or the nixbld user running the tests? I verified that the library works when invoked from a Nix shell by a regular user.

pkgs/development/python-modules/setproctitle/default.nix

@@ -5,6 +5,7 @@
   setuptools,
   pytestCheckHook,
   procps,
+  stdenv,
 }:
 
 buildPythonPackage rec {
@@ -26,6 +27,9 @@ buildPythonPackage rec {
     procps
   ];
 
+  # Setting the process title fails on macOS in the Nix builder environment (regardless of sandboxing)
+  disabledTests = lib.optionals stdenv.hostPlatform.isDarwin [ "test_setproctitle_darwin" ];
+
   pythonImportsCheck = [ "setproctitle" ];
 
   meta = {