### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When attempting to list roles where permission boundaries are attached the response cannot be serialized 

`aws --endpoint-url=http://localhost:4566 iam list-roles --region ap-southeast-2`
```
An error occurred (InternalError) when calling the ListRoles operation (reached max retries: 2): exception while calling iam.ListRoles: Invalid type when serializing AttachedPermissionsBoundary: '<Element 'member' at 0xffff8275ef20>' cannot be parsed to structure.
```

### Expected Behavior

Expect that all roles are listed

### How are you starting LocalStack?

With a docker-compose file

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

    docker run localstack/localstack

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

* Create an IAM policy
* Create an IAM role which used the policy as a permission boundary
* Attempt to list all roles with `aws --endpoint-url=http://localhost:4566 iam list-roles --region ap-southeast-2`


### Environment

```markdown
- OS: MacOS
- LocalStack: latest
```


### Anything else?

_No response_
from localstack.utils.aws import aws_stack
from localstack.utils.aws.aws_stack import extract_access_key_id_from_auth_header
from localstack.utils.common import short_uid
from localstack.utils.patch import patch
SERVICE_LINKED_ROLE_PATH_PREFIX = "/aws-service-role"
ADDITIONAL_MANAGED_POLICIES = {
    "AWSLambdaExecute": {
        "Arn": "arn:aws:iam::aws:policy/AWSLambdaExecute",
        "Path": "/",
        "CreateDate": "2017-10-20T17:23:10+00:00",
        "DefaultVersionId": "v4",
        "Document": {
            "Version": "2012-10-17",
            "Statement": [
                {
                    "Effect": "Allow",
                    "Action": ["logs:*"],
                    "Resource": "arn:aws:logs:*:*:*",
                },
                {
                    "Effect": "Allow",
                    "Action": ["s3:GetObject", "s3:PutObject"],
                    "Resource": "arn:aws:s3:::*",
                },
            ],
        },
        "UpdateDate": "2019-05-20T18:22:18+00:00",
    }
}
def get_iam_backend(context: RequestContext) -> IAMBackend: