bpo-40275: Use new test.support helper submodules in tests (GH-21315)

diff --git a/Lib/test/test_pty.py b/Lib/test/test_pty.py
index 9c32467..7ca0557 100644
--- a/Lib/test/test_pty.py
+++ b/Lib/test/test_pty.py
@@ -1,4 +1,5 @@
-from test.support import verbose, import_module, reap_children
+from test.support import verbose, reap_children
+from test.support.import_helper import import_module
 
 # Skip these tests if termios is not available
 import_module('termios')