[3.13] gh-120579: Guard _testcapi import in test_free_threading (GH-120580) (#120583)

gh-120579: Guard `_testcapi` import in `test_free_threading` (GH-120580)
(cherry picked from commit 0c0348a)

Co-authored-by: Nikita Sobolev <[email protected]>

Author: miss-islington

Lib/test/test_free_threading/test_dict.py

@@ -8,7 +8,10 @@
 from threading import Thread
 from unittest import TestCase
 
-from _testcapi import dict_version
+try:
+    import _testcapi
+except ImportError:
+    _testcapi = None
 
 from test.support import threading_helper
 
@@ -139,7 +142,9 @@ def writer_func(l):
             for ref in thread_list:
                 self.assertIsNone(ref())
 
+    @unittest.skipIf(_testcapi is None, 'need _testcapi module')
     def test_dict_version(self):
+        dict_version = _testcapi.dict_version
         THREAD_COUNT = 10
         DICT_COUNT = 10000
         lists = []