deploy.py: Fix when running with Python 3.6

Which happens to be the default version on macOS 10.14.
Python 3.6 does not return a sensible default encoding if you don't
fiddle with your environment (like explicitly setting LANG). Fall back
to UTF-8.

Change-Id: I12534e4745e9c29b40a02c4946d8079d395cc650
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

scripts/common.py

@@ -30,6 +30,8 @@ import subprocess
 import sys
 
 encoding = locale.getdefaultlocale()[1]
+if not encoding:
+    encoding = 'UTF-8'
 
 def is_windows_platform():
     return sys.platform.startswith('win')