util: Migrate chargen to python3

BUG=chromium:1031705
BRANCH=master
TEST=Output is the same with python2

Signed-off-by: kerker <kerker@chromium.org>
Change-Id: Ice9bb885fe862b298c55c29c05d7f7eb4a2bead0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2425984
Reviewed-by: Jett Rink <jettrink@chromium.org>

util/chargen

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 # Copyright 2019 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -62,7 +62,7 @@ def main(args):
     try:
         chargen(modulo, max_chars)
     except KeyboardInterrupt:
-        print
+        print()
 
 if __name__ == '__main__':
     main(sys.argv[1:])