bpo-40275: Use new test.support helper submodules in tests (GH-21412)

diff --git a/Lib/test/test_pkgutil.py b/Lib/test/test_pkgutil.py
index b162f99..bf9722a 100644
--- a/Lib/test/test_pkgutil.py
+++ b/Lib/test/test_pkgutil.py
@@ -1,4 +1,6 @@
-from test.support import run_unittest, unload, check_warnings, CleanImport
+from test.support import run_unittest
+from test.support.import_helper import unload, CleanImport
+from test.support.warnings_helper import check_warnings
 import unittest
 import sys
 import importlib