cosmetic: fix import for previous commit

Change-Id: I44eed9a449be8202cea08894bf1c428f52e2625d
diff --git a/src/osmo-gsm-tester.py b/src/osmo-gsm-tester.py
index b834711..0137f25 100755
--- a/src/osmo-gsm-tester.py
+++ b/src/osmo-gsm-tester.py
@@ -66,6 +66,7 @@
 created, which will collect logs and reports.
 '''
 
+import sys
 from osmo_gsm_tester import __version__
 from osmo_gsm_tester import trial, suite, log, config