### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

I am running an SNS topic that publishes to a lambda function. The localstack code reads a type byte object from the lambda function invocation payload [here](https://github.com/localstack/localstack/blob/master/localstack/services/sns/publisher.py#L187) and then tries to dump the result into json [here](https://github.com/localstack/localstack/blob/master/localstack/services/sns/publisher.py#L863) which results in the following error:
```
sns_pub_0] l.services.sns.publisher   : Unable to run Lambda function on SNS message: Object of type bytes is not JSON serializable
```

### Expected Behavior

The payload bytes should be converted to a string before being dumped to json. The error should not be thrown.

### 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-compose up
(Using the standard docker-compose.yaml)

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

```
awslocal sns publish --message file://sns/message.json --topic-arn arn:aws:sns:us-east-1:000000000000:<topic_name>
```

### Environment

```markdown
- OS: macOS Ventura 13.2.1
- LocalStack: latest
```


### Anything else?

_No response_
"""
        Base method for publishing the message. It is up to the child class to implement its way to publish the message
        :param context: the SnsPublishContext created by the caller, containing the necessary data to publish the
        message
        :param subscriber: the subscription data
        :return:
        """
        raise NotImplementedError
    def prepare_message(self, message_context: SnsMessage, subscriber: SnsSubscription) -> str:
        """
        Returns the message formatted in the base SNS message format. The base SNS message format is shared amongst
        SQS, HTTP(S), email-json and Firehose.
        See https://docs.aws.amazon.com/sns/latest/dg/sns-sqs-as-subscriber.html
        :param message_context: the SnsMessage containing the message data
        :param subscriber: the SNS subscription
        :return: formatted SNS message body in a JSON string
        """
        return create_sns_message_body(message_context, subscriber)
class EndpointPublisher(abc.ABC):