chroot_version_hooks.d: migrate the SDK to Python 3.6

Make sure the SDK no longer includes Python 3.4 and switch default
Python 3 over to 3.6.

BUG=chromium:982409
TEST=CQ passes

Change-Id: I6f873240d8084bfaad63ec45771404ea7c4d3c3e
Reviewed-on: https://chromium-review.googlesource.com/1722397
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>
Reviewed-by: Alex Klein <saklein@chromium.org>
1 file changed