Problem with a specific op MatrixTriangularSolve

[tperciano]

Describe the bug

I'm converting a tensorflow model to onnx but I get an error regarding an unsupported op:

2022-03-22 14:06:04,087 - ERROR - Tensorflow op [StatefulPartitionedCall/triangular_solve/MatrixTriangularSolve: MatrixTriangularSolve] is not supported
2022-03-22 14:06:04,088 - ERROR - Tensorflow op [StatefulPartitionedCall/triangular_solve_1/MatrixTriangularSolve: MatrixTriangularSolve] is not supported
2022-03-22 14:06:04,092 - ERROR - Unsupported ops: Counter({'MatrixTriangularSolve': 2})

Urgency

Extremely important to get it to work.

System information

OS Platform: Linux
Tensorflow Version: 2.8
Python version: 3.8

To Reproduce

I ran the command :
python -m tf2onnx.convert --opset 11 --saved-model ./saved_model/ --output my_model.onnx

Thanks in advance!