python3Packages.typer: disable failing tests on darwin

these all seem to stem from the shellingham package being unable to
detect the shell (even if we provide `ps` to it), likely related to
a known issue

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

···
 { lib
+, stdenv
 , buildPythonPackage
 , fetchPypi
 , click
···
   preCheck = ''
     export HOME=$(mktemp -d);
   '';
+  disabledTests = lib.optionals stdenv.isDarwin [
+    # likely related to https://github.com/sarugaku/shellingham/issues/35
+    "test_show_completion"
+    "test_install_completion"
+  ];
 
   pythonImportsCheck = [ "typer" ];