bpo-40275: Use new test.support helper submodules in tests (GH-21314)

diff --git a/Lib/test/test_nis.py b/Lib/test/test_nis.py
index 21074c6..a22142f 100644
--- a/Lib/test/test_nis.py
+++ b/Lib/test/test_nis.py
@@ -1,8 +1,10 @@
 from test import support
+from test.support import import_helper
 import unittest
 
+
 # Skip test if nis module does not exist.
-nis = support.import_module('nis')
+nis = import_helper.import_module('nis')
 
 
 class NisTests(unittest.TestCase):