Missing converter for OpOverload(op='aten._grouped_mm', overload='default')

```python import torch class Model(torch.nn.Module): def forward(self, a, b): return torch.nn.functional.grouped_mm( a.to(torch.bfloat16), b.transpose(-2, -1).to(torch.bfloat16) ).to(torch.float32) G, M, N, K = 4, 16, 32, 64 a = torch.randn(G, M, K, device="cpu", dtype=torch.float32) b = torch.randn(G, N, K, device="cpu", dtype=torch.float32) model = Model() expected = model(a, b) ep = torch.export.export(model, (a, b)) names = [str(n.target) for n in ep.graph.nodes] assert "aten._grouped_mm.default" in names epo = torch.onnx.export( model, (a, b), dynamic_shapes=({0: "G", 1: "M", 2: "K"}, {0: "G", 1: "N", 2: "K"}) ) ``` ``` <class 'torch.onnx._internal.exporter._errors.DispatchError'>: No ONNX function found for <OpOverload(op='aten._grouped_mm', overload='default')>. Failure message: No decompositions registered for the real-valued input ``` Issue met with ``microsoft/OptiMind-SFT``.