[code-health] Run common/py_utils/PRESUBMIT.py under Python 3
[code-health] Run common/py_utils/PRESUBMIT.py under Python 3

The code is already Python 3-compatible, this makes the presubmit
itself run under Python 3.

Bug: chromium:942720
Change-Id: I67d625e839e98391d8ff84da940a7fc481aa23e3
Reviewed-on: https://chromium-review.googlesource.com/c/catapult/+/3324025
Auto-Submit: Fabrice de Gans <6f44d4a9f585af9d13bfe822fdf9ff664b2ec988@chromium.org>
Reviewed-by: Deep Roy <196de8ecef43ff77ba1a773ccd52374e3849c302@chromium.org>
Commit-Queue: Deep Roy <196de8ecef43ff77ba1a773ccd52374e3849c302@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult