Avoid deprecated x.T in default ONNX Transpose handling (#2)

* Initial plan

* Fix default transpose warning

Co-authored-by: mshr-h <8973217+mshr-h@users.noreply.github.com>

* Remove added transpose regression test

Co-authored-by: mshr-h <8973217+mshr-h@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: mshr-h <8973217+mshr-h@users.noreply.github.com>

Author: Copilot

src/onnx2fx/ops/tensor.py

@@ -142,7 +142,10 @@ def transpose(builder: "GraphBuilder", node: onnx.NodeProto) -> torch.fx.Node:
     perm = get_attribute(node, "perm")
     if perm is None:
         # Default: reverse all dimensions
-        return builder.call_function(lambda t: t.T, args=(x,))
+        return builder.call_function(
+            lambda t: torch.permute(t, tuple(range(t.ndim - 1, -1, -1))),
+            args=(x,),
+        )
     return builder.call_function(torch.permute, args=(x, perm))