Implement opset 16 #234
Description
https://github.com/onnx/onnx/blob/main/docs/Changelog.md#version-16-of-the-default-onnx-operator-set
Operators to update:
- GreaterOrEqual
- LeakyRelu
- LessOrEqual
- PRelu
- Where
- Identity
Also:
- Update max supported opset constant