tests: always disable on the nogil build

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

Author: henryiii

CMakePresets.json

@@ -6,7 +6,7 @@
       "displayName": "Default",
       "binaryDir": "build",
       "generator": "Ninja",
-      "errors": {
+      "warnings": {
         "dev": true,
         "deprecated": true
       },

tests/test_gil_scoped.py

@@ -2,6 +2,7 @@
 
 import multiprocessing
 import sys
+import sysconfig
 import threading
 import time
 
@@ -10,8 +11,9 @@
 import env
 from pybind11_tests import gil_scoped as m
 
+
 skipif_not_free_threaded = pytest.mark.skipif(
-    not getattr(sys, "_is_gil_enabled", lambda: True)(),
+    sysconfig.get_config_var("Py_GIL_DISABLED"),
     reason="Flaky without the GIL",
 )