Pin flatbuffers version (#1511)

Signed-off-by: Tom Wildenhain <tomwi@microsoft.com>

Author: TomWildenhain-Microsoft

setup.py

@@ -81,7 +81,7 @@ def run(self):
  author='onnx@microsoft.com',
  author_email='onnx@microsoft.com',
  url='https://github.com/onnx/tensorflow-onnx',
- install_requires=['numpy>=1.14.1', 'onnx>=1.4.1', 'requests', 'six', 'flatbuffers'],
+ install_requires=['numpy>=1.14.1', 'onnx>=1.4.1', 'requests', 'six', 'flatbuffers~=1.12'],
  classifiers=[
  'Development Status :: 5 - Production/Stable',
  'Intended Audience :: Developers',