### 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_
self, service_name, expected_role, aws_client
    ):
        role_name = None
        try:
            service_linked_role = aws_client.iam.create_service_linked_role(
                AWSServiceName=service_name
            )
            role_name = service_linked_role["Role"]["RoleName"]
            assert role_name == expected_role
        finally:
            if role_name:
                aws_client.iam.delete_service_linked_role(RoleName=role_name)
    @pytest.mark.aws_validated
    def test_update_assume_role_policy(self, snapshot, aws_client):