Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: chapman73

onnxscript/utils/model_proto_to_function_proto.py

@@ -39,7 +39,7 @@ def _initializers_to_constants(model: onnx.ModelProto) -> onnx.ModelProto:
 
 
 def convert_model_proto_to_function_proto(
-    model: onnx.ModelProto, domain, name
+    model: onnx.ModelProto, domain: str, name: str
 ) -> onnx.FunctionProto:
     """Converts an arbitrary ModelProto to a FunctionProto.