pywalt: drop python2 support

Nothing seems to need this, so drop it.

BUG=chromium:951561
TEST=CQ passes

Change-Id: Idf2cb85033e5b2c7a418d24e613f2f69610fc872
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/chromiumos-overlay/+/2595714
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Nicolas Boichat <drinkcat@chromium.org>
3 files changed