bpo-40275: Use new test.support helper submodules in tests (GH-21449)

diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index d659f36..bdb9f02 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -1,7 +1,9 @@
 import unittest
 import sys
 
-from test.support import import_fresh_module, run_unittest
+from test.support import run_unittest
+from test.support.import_helper import import_fresh_module
+
 
 TESTS = 'test.datetimetester'