remove unused import

python3 does not have cStringIO

Bug: 1012230
Change-Id: I6cd0329a49042c1ca90dcc77baf0566a7eb739e3
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/python-adb/+/1852386
Auto-Submit: Takuto Ikuta <[email protected]>
Reviewed-by: Marc-Antoine Ruel <[email protected]>
diff --git a/smoke_test.py b/smoke_test.py
index bf5c39b..6fbc1e3 100755
--- a/smoke_test.py
+++ b/smoke_test.py
@@ -19,7 +19,6 @@
 """
 
 import argparse
-import cStringIO
 import logging
 import os
 import pipes