Run clang update script under python3 in angle Bug: chromium:1261812 Change-Id: I01b0f6048ffa2273f6941ad3e6ca750cd61852f3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3246592 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>