pylint: upgrade to 1.6 (and pull in its new deps)

While cros lint should only use pylint from depot_tools, we still
want to keep these versions in sync in case devs run things by hand.

BUG=chromium:866772
TEST=CQ passes

Change-Id: Ie2f4f2bc78f195891698acbe353f7ddb196165a8
Reviewed-on: https://chromium-review.googlesource.com/1769200
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
17 files changed