[ONNX] clarifies error message for upsample interpolation mode (llvm#3940)

Changes the messaging for an `onnx.Upsample` match failure in `TorchOnnxToTorch`.

Author: bjacobgordon

lib/Conversion/TorchOnnxToTorch/DefaultDomainQtoZ.cpp

@@ -3331,8 +3331,8 @@ void mlir::torch::onnx_c::populateDefaultDomainQtoZ(
 
         if (mode != "nearest" && mode != "linear")
           return rewriter.notifyMatchFailure(
-              binder.op, "unsupported interpolation mode other than nearest, "
-                         "linear");
+              binder.op,
+              R"(Expected valid interpolation mode: "nearest" | "linear")");
 
         int64_t resultRank = resultType.getSizes().size();
         if (resultRank > 5)