optimum

4016c17d - ONNX transformation to cast int64 constants to int32 when possible (#655)

ONNX transformation to cast int64 constants to int32 when possible (#655) * add function to convert int64 constants to int32 * add utils file * add in init * add doc * remove onnx check * fix transformation and test * Update optimum/onnxruntime/modeling_decoder.py * more explicit naming