### 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_
lambda: len(server.log) >= 1,
            timeout=5,
        )
        sub_request, _ = server.log[0]
        payload = sub_request.get_json(force=True)
        assert payload["Type"] == "SubscriptionConfirmation"
        assert sub_request.headers["x-amz-sns-message-type"] == "SubscriptionConfirmation"
        subscribe_url = payload["SubscribeURL"]
        service_url, subscribe_url_path = payload["SubscribeURL"].rsplit("/", maxsplit=1)
        confirm_subscribe_request = requests.get(subscribe_url)
        confirm_subscribe = xmltodict.parse(confirm_subscribe_request.content)
        assert (
            confirm_subscribe["ConfirmSubscriptionResponse"]["ConfirmSubscriptionResult"][
                "SubscriptionArn"
            ]
            == http_subscription_arn
        )
        subscription_attributes = sns_client.get_subscription_attributes(
            SubscriptionArn=http_subscription_arn
        )
        assert subscription_attributes["Attributes"]["PendingConfirmation"] == "false"
        server.stop()
        wait_for_port_closed(server.port)
        message = "test_dlq_external_http_endpoint"
        sns_client.publish(TopicArn=topic_arn, Message=message)
        response = sqs_client.receive_message(QueueUrl=dlq_url, WaitTimeSeconds=3)
        assert (
            len(response["Messages"]) == 1
        ), f"invalid number of messages in DLQ response {response}"
        if raw_message_delivery: