Fix aten_pow when first input is a python constant

onnxscript/function_libs/torch_lib/ops/core.py

@@ -6652,11 +6652,13 @@
         "aten::pow.Tensor_Scalar",
         "_operator::pow",
     ),
-    traceable=True,
+    trace_only=True,
 )
 def aten_pow(self: TReal, exponent: TTensor) -> TReal:
     """pow(Tensor self, Tensor exponent) -> Tensor"""
 
+    if isinstance(self, (int, float)) and hasattr(exponent, "dtype"):
+        return op.Pow(op.Cast(self, to=exponent.dtype), exponent)
     return op.Pow(self, exponent)