🚀 Feature

When exporting and ONNX model add the option to use INT32 matrix instead of INT64 as INT64 is not supported by OpenCV

Motivation

I exported the model as an ONNX model, the I tried to import it in OpenCV 4.2.0 using cv2.dnn.readNetFromONNX(model_path) and I got the following error:

self.model = cv2.dnn.readNetFromONNX(model_path)
cv2.error: OpenCV(4.2.0) /io/opencv/modules/dnn/src/onnx/onnx_importer.cpp:101: error: (-211:One of the arguments' values is out of range) Input is out of OpenCV 32S range in function 'convertInt64ToInt32'

Pitch

I want to have a parameter when exporting to be able to select INT32 matrix.

Alternatives

An alternative solution could be to just use INT32 always instead of INT64.

Additional context

opencv/opencv#14830