message: Update tensorboard dependency to 1.9.x
diff: @@ -55,7 +55,7 @@ REQUIRED_PACKAGES = [
  'six >= 1.10.0',
  'protobuf >= 3.4.0',
  'setuptools <= 39.1.0',
  - 'tensorboard >= 1.8.0, < 1.9.0',
  + 'tensorboard >= 1.9.0, < 1.10.0',
  'termcolor >= 1.1.0',
  ]
  