Update autocast.py to fix attribute creation error (#2365)

This change should fix the type of errors like below (reported in
pytorch/pytorch#153214 (comment)):

Author: justinchuby

onnxscript/_internal/autocast.py

@@ -45,7 +45,7 @@ def pyvalue_to_onnx_attribute(
     key: str,
     value: Any,
     name_generator: Callable[[], str],
-    attr_type: Optional[onnx.AttributeProto.AttributeType] = None,
+    attr_type: onnx.AttributeProto.AttributeType | None = None,
 ) -> onnx.AttributeProto:
     """Helper function to create an ONNX AttributeProto.
 

onnxscript/converter.py

@@ -298,7 +298,7 @@ def generate_unique_name(self, candidate: str = "tmp") -> str:
         return r
 
     def _make_onnx_attr(
-        self, attrname: str, attrval: Any, attrtype: Optional[int] = None
+        self, attrname: str, attrval: Any, attrtype: int | None = None
     ) -> irbuilder.IRAttributeValue:
         def tensor_name_generator() -> str:
             """Return name to be used for tensor, if we need to create one."""
@@ -518,8 +518,8 @@ def _translate_attr(
             if attr_meta and attr_meta.required:
                 self.fail(expr, f"Attribute '{attr_name}' is required.")
             return None
-        attr_type = attr_meta.type if attr_meta else None
-        attr = self._make_onnx_attr(attr_name, val, attr_type)
+        attr_type = int(attr_meta.type) if attr_meta else None
+        attr = self._make_onnx_attr(attr_name, val, attrtype=attr_type)
         if attr_meta and (attr.type != attr_meta.type):
             self.fail(
                 expr,

onnxscript/evaluator.py

@@ -420,7 +420,7 @@ def make_tensor_name() -> str:
             return f"attr_{key}"
 
         return autocast.pyvalue_to_onnx_attribute(
-            key, value, make_tensor_name, schema.attributes[key].type
+            key, value, make_tensor_name, int(schema.attributes[key].type)
         )
 
     # Construct ONNX model with a single op call: