[ONNX] Skip import test for experimental files (pytorch#94552)

`torch.onnx._internal.fx` is experimental and is not imported when `import torch`/`import torch.onnx`.
Need to skip it in this test as it depends on `onnx-script`.
Pull Request resolved: pytorch#94552
Approved by: https://github.com/kit1980

test/test_testing.py

@@ -1987,6 +1987,7 @@ def test_circular_dependencies(self) -> None:
                            "torch.contrib.",  # something weird
                            "torch.testing._internal.distributed.",  # just fails
                            "torch.ao.pruning._experimental.",  # depends on pytorch_lightning, not user-facing
+                           "torch.onnx._internal.fx",  # depends on onnx-script
                            ]
         # See https://github.com/pytorch/pytorch/issues/77801
         if not sys.version_info >= (3, 9):