ci: update `buildifier` to 3.0.0 (#3689)
ci: update `buildifier` to 3.0.0 (#3689)

Summary:
This appears to be needed for the `load-on-top` to actually have any
effect: we currently suppress that lint, but even after enabling it lint
still passes with Buildifier 0.29.0 and properly fails only with a later
version.

wchargin-branch: ci-buildifier-3.0.0

tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard