Int8 Models using custom Ops in the model zoo

[cjvolzka]

Bug Report

Which model does this pertain to?

I haven't done an exhaustive search so there are likely more. So far I've found:

• https://github.com/onnx/models/blob/main/vision/classification/alexnet/model/bvlcalexnet-12-int8.onnx
• https://github.com/onnx/models/blob/main/vision/classification/mobilenet/model/mobilenetv2-12-int8.onnx

Describe the bug

I found some models in the zoo contain a QLinearAdd which does not exist in the ONNX Operators list. (There are other QLinear* operators but no QLinearAdd)

Reproduction instructions

View models in Netron. Search for QLinearAdd