nebraska: Move it to python3

BUG=chromium:998225
TEST=nebraska_unittest.py

Change-Id: I6c6183d38265e6ab66811e95e2abe3a3e641effb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2837692
Tested-by: Amin Hassani <ahassani@chromium.org>
Auto-Submit: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
1 file changed