Integration with ONNX 1.19.0

[yuanyao-nv]

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Describe the feature request

We are releasing ONNX 1.19.0. A release branch has been created (https://github.com/onnx/onnx/tree/rel-1.19.0). The planned release date is late August 2025. Release candidates are also available from TestPyPI: pip install -i https://test.pypi.org/simple/ --pre onnx

It is important to test the integration of ONNX release branch into tensorflow-onnx ASAP so that any issues and incompatibilities can be detected and resolved before the ONNX release. Please open an issue on the ONNX repo for issues encountered.

Up-to-date release info can be found at (https://github.com/onnx/onnx/wiki/Logistics-for-ONNX-Release-1.19.0).

Thank you!

Describe scenario use case