message: build: update protobuf to to fix Skylib import.
  This might be an overkill, but we're already tracking master branch,
  and it silences the deprecation warning.
diff: @@ -151,14 +151,15 @@ REPOSITORY_LOCATIONS = dict(
  urls = ["https://github.com/google/googletest/archive/release-1.8.1.tar.gz"],
  ),
  com_google_protobuf = dict(
  - sha256 = "3d610ac90f8fa16e12490088605c248b85fdaf23114ce4b3605cdf81f7823604",
  - strip_prefix = "protobuf-fa252ec2a54acb24ddc87d48fed1ecfd458445fd",
  + sha256 = "46f1da3a6a6db66dd240cf95a5553198f7c6e98e6ac942fceb8a1cf03291d96e",
  + strip_prefix = "protobuf-7492b5681231c79f0265793fa57dc780ae2481d6",
  # TODO(htuch): Switch back to released versions for protobuf when a release > 3.6.0 happens
  # that includes:
  # - https://github.com/protocolbuffers/protobuf/commit/f35669b8d3f46f7f1236bd21f14d744bba251e60
  # - https://github.com/protocolbuffers/protobuf/commit/6a4fec616ec4b20f54d5fb530808b855cb664390
  # - https://github.com/protocolbuffers/protobuf/commit/fa252ec2a54acb24ddc87d48fed1ecfd458445fd
  - urls = ["https://github.com/protocolbuffers/protobuf/archive/fa252ec2a54acb24ddc87d48fed1ecfd458445fd.tar.gz"],
  + # - https://github.com/protocolbuffers/protobuf/commit/7492b5681231c79f0265793fa57dc780ae2481d6
  + urls = ["https://github.com/protocolbuffers/protobuf/archive/7492b5681231c79f0265793fa57dc780ae2481d6.tar.gz"],
  ),
  grpc_httpjson_transcoding = dict(
  sha256 = "dedd76b0169eb8c72e479529301a1d9b914a4ccb4d2b5ddb4ebe92d63a7b2152",
  