Enable version converter for torch>=2.6 (#2111)

Enable version converter for torch>=2.6

Author: shubhambhokare1

onnxscript/_framework_apis/torch_2_6.py

@@ -14,10 +14,9 @@
 ]
 from typing import TYPE_CHECKING
 
-from onnxscript import ir, optimizer
+from onnxscript import ir, optimizer, version_converter
 from onnxscript._framework_apis.torch_2_5 import (
     check_model,
-    convert_version,
     get_torchlib_ops,
     save_model_with_external_data,
 )
@@ -32,6 +31,14 @@ def optimize(model: ir.Model) -> ir.Model:
     return model
 
 
+def convert_version(model: ir.Model, target_version: int) -> ir.Model:
+    """Convert the model to the specified ONNX opset version."""
+    if target_version < 18:
+        return model
+    version_converter.convert_version(model, target_version)
+    return model
+
+
 def torchlib_opset() -> Opset18:
     """Return the default opset for torchlib."""
     import onnxscript  # pylint: disable=import-outside-toplevel