Failed to convert 'onnx.Loop' to StableHLO dialect

[XuLin-1017]

Hi onnx team, I'm trying to convert 'onnx.Loop' operation to StableHLO using ONNX-MLIR. However, I noted that there is no conversion from 'onnx.Loop' to StableHLO implemented in ONNX-MLIR. [1/3] Thu Oct 16 15:20:10 2025 (0s) Importing ONNX Model to MLIR Module from "yolov3-12.onnx" [2/3] Thu Oct 16 15:20:11 2025 (1s) Compiling and Optimizing MLIR Module failed to legalize operation 'onnx.Loop' that was explicitly marked illegal