### 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_
secret_id_repl = f"<SecretId-{index}idx>"
        arn_part_repl = f"<ArnPart-{index}idx>"
        secret_id: str = create_secret_res["Name"]
        arn_part: str = "".join(create_secret_res["ARN"].rpartition("-")[-2:])
        return [
            RegexTransformer(arn_part, arn_part_repl),
            RegexTransformer(secret_id, secret_id_repl),
        ]
    @s
    def sfn_sm_create_arn(create_sm_res: CreateStateMachineOutput, index: int):
        arn_part_repl = f"<ArnPart_{index}idx>"
        arn_part: str = "".join(create_sm_res["stateMachineArn"].rpartition(":")[-1])
        return RegexTransformer(arn_part, arn_part_repl)
    @s
    def sfn_sm_exec_arn(start_exec: StartExecutionOutput, index: int):
        arn_part_repl = f"<ExecArnPart_{index}idx>"
        arn_part: str = "".join(start_exec["executionArn"].rpartition(":")[-1])
        return RegexTransformer(arn_part, arn_part_repl)
    @s
    def stepfunctions_api():