Add anaconda cloud pyg

[billchenchina]

PyG is a library built upon PyTorch to easily write and train Graph Neural Networks for a wide range of applications related to structured data. PyG is both friendly to machine learning researchers and first-time users of machine learning toolkits.

Ref: https://github.com/tuna/issues/issues/1583

Ref: https://github.com/hitlug/issues/issues/47