bpo-40275: Use new test.support helper submodules in tests (GH-21317)

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 925a6bc..c5fbd87 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -7,7 +7,8 @@
 import unittest
 import re
 from test import support
-from test.support import TESTFN, Error, captured_output, unlink, cpython_only, ALWAYS_EQ
+from test.support import Error, captured_output, cpython_only, ALWAYS_EQ
+from test.support.os_helper import TESTFN, unlink
 from test.support.script_helper import assert_python_ok
 import textwrap