Update shebang line for update_device.py.

It is no longer python2 compatible.

Test: pass
Change-Id: Ibb0b7aa33ba1be3e2f40893da70f81c858479f7e
diff --git a/scripts/update_device.py b/scripts/update_device.py
index 7313d7c..f672cda 100755
--- a/scripts/update_device.py
+++ b/scripts/update_device.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright (C) 2017 The Android Open Source Project
 #