[Bug Report]

**Link to the notebook**
[Add the link to the notebook.
](https://github.com/aws/amazon-sagemaker-examples/blob/default/%20%20%20%20%20%20build_and_train_models/sm-marketplace_build_model_package_for_listing/sm-marketplace_build_model_package_for_listing.ipynb)

**Describe the bug**
As going through the notebook I get the following error

**To reproduce**
The only thing I have changed in the notebook is that I have used an existing sagemaker role and not using the `role = get_execution_role()` in the notebooks. Another thing I have changed is Validation Specificaiton.ValidationRole in the `sagemaker.create_model_package` from role to the arn of the aforementioned role.
The role was giving an errors as it should be the arn of the role. If I let this parameter be role it was giving the following error
```ClientError: An error occurred (ValidationException) when calling the CreateModelPackage operation: 1 validation
error detected: Value 'AmazonSageMaker-ExecutionRole-20230901T123456' at 'validationSpecification.validationRole'
failed to satisfy constraint: Member must satisfy regular expression pattern:
arn:aws[a-z\-]*:iam::\d{12}:role/?[a-zA-Z_0-9+=,.@\-_/]+```

Open build_and_train_models/sm-marketplace_build_model_package_for_listing/sm-marketplace_build_model_package_for_listing.ipynb and reproduce the CreateModelPackage call using an existing SageMaker role ARN. Inspect ValidationSpecification.ValidationRole and the reported validation error. Done means the notebook reaches model package creation without the ValidationRole format error.

Written by the indexing model from the issue text.