fix test_platform (os was not imported)
diff --git a/Lib/test/test_platform.py b/Lib/test/test_platform.py
index f337fba..6275a6a 100644
--- a/Lib/test/test_platform.py
+++ b/Lib/test/test_platform.py
@@ -1,4 +1,5 @@
 import sys
+import os
 import unittest
 import platform