### 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_
"Resource": ["arn:aws:s3:::bucket_name"],
                }
            ],
        }
        aws_client.iam.create_role(
            RoleName=role_name,
            AssumeRolePolicyDocument=json.dumps(assume_policy_document),
        )
        policy_arn = aws_client.iam.create_policy(
            PolicyName=policy_name, Path="/", PolicyDocument=json.dumps(policy_document)
        )["Policy"]["Arn"]
        policy_arns.append(policy_arn)
        
        for policy_arn in policy_arns:
            rs = aws_client.iam.attach_role_policy(RoleName=role_name, PolicyArn=policy_arn)
            assert rs["ResponseMetadata"]["HTTPStatusCode"] == 200
        try:
            
            aws_client.iam.delete_role(RoleName=role_name)
            pytest.fail("This call should not be successful as the role has policies attached")
        except ClientError as e:
            assert e.response["Error"]["Code"] == "DeleteConflict"
        for policy_arn in policy_arns:
            rs = aws_client.iam.detach_role_policy(RoleName=role_name, PolicyArn=policy_arn)
            assert rs["ResponseMetadata"]["HTTPStatusCode"] == 200
        
        rs = aws_client.iam.delete_role(RoleName=role_name)
        assert rs["ResponseMetadata"]["HTTPStatusCode"] == 200
        aws_client.iam.delete_policy(PolicyArn=policy_arn)
    def test_simulate_principle_policy(self, aws_client):