### 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_
"""Register the platform endpointmessages retrospection endpoint as an internal LocalStack endpoint."""
    router.add(SNSServicePlatformEndpointMessagesApiResource())
def _format_platform_endpoint_messages(sent_messages: List[Dict[str, str]]):
    """
    This method format the messages to be more readable and undo the format change that was needed for Moto
    Should be removed once we refactor SNS.
    """
    validated_keys = [
        "TargetArn",
        "TopicArn",
        "Message",
        "MessageAttributes",
        "MessageStructure",
        "Subject",
        "MessageId",
    ]
    formatted_messages = []
    for sent_message in sent_messages:
        msg = {
            key: value if key != "Message" else json.dumps(value)
            for key, value in sent_message.items()
            if key in validated_keys
        }
        formatted_messages.append(msg)
    return formatted_messages
class SNSServicePlatformEndpointMessagesApiResource: