scripts: convert random standalone programs to python3 only

Nothing imports these, so should be safe to convert.

BUG=chromium:997354
TEST=CQ passes

Change-Id: Ic0ddd990c7bb78a020990a9cff01ae2a27f29e1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2066684
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/setup_board.py b/scripts/setup_board.py
index 428ecce..adfa3e3 100644
--- a/scripts/setup_board.py
+++ b/scripts/setup_board.py
@@ -13,6 +13,8 @@
 
 from __future__ import print_function
 
+import sys
+
 from chromite.lib import build_target_util
 from chromite.lib import commandline
 from chromite.lib import cros_build_lib
@@ -20,6 +22,9 @@
 from chromite.service import sysroot
 
 
+assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
+
+
 def GetParser():
   """Build the argument parser."""
   # TODO(crbug.com/922144) Remove underscore separated arguments and the