python311Packages.pytest-django: drop pytest-xdist

A handful of tests fails because of this.
One of the errors is: django.db.utils.OperationalError: no such table: app_item
which suggests that the tests in general don't work in parallel.

I don't think that worked since 843ea199a3

see also issue tracker https://github.com/pytest-dev/pytest-django/issues/867

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

@@ -7,7 +7,6 @@
 , django-configurations
 , pytest
 , pytestCheckHook
-, pytest-xdist
 }:
 buildPythonPackage rec {
   pname = "pytest-django";
@@ -35,7 +34,6 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     django-configurations
     pytestCheckHook
-    pytest-xdist
   ];
 
   preCheck = ''