bpo-40275: Use new test.support helper submodules in tests (GH-21219)

diff --git a/Lib/test/audiotests.py b/Lib/test/audiotests.py
index d3e8e9e..9d6c4cc 100644
--- a/Lib/test/audiotests.py
+++ b/Lib/test/audiotests.py
@@ -1,4 +1,5 @@
-from test.support import findfile, TESTFN, unlink
+from test.support import findfile
+from test.support.os_helper import TESTFN, unlink
 import array
 import io
 import pickle