message: Update gRPC dependency.
diff: @@ -112,10 +112,10 @@ http_archive(
  http_archive(
  name = "com_github_grpc_grpc",
  urls = [
  - "https://github.com/grpc/grpc/archive/v1.20.0.tar.gz"
  + "https://github.com/grpc/grpc/archive/v1.21.3.tar.gz"
  ],
  - sha256 = "01c5e617d098a33672ddb640d0e50831fb7c613999435e5dcf115021abde6b9a",
  - strip_prefix = "grpc-1.20.0",
  + sha256 = "50747c8939c535b1059f19534de263eb9b7570b5347390fb24b0bbce8763e9a4",
  + strip_prefix = "grpc-1.21.3",
  )
  # Binds needed by gRPC.
  