### 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_
message_type = message_context.type or "Notification"
    protocol = subscriber["Protocol"]
    message_content = message_context.message_content(protocol)
    if message_type == "Notification" and is_raw_message_delivery(subscriber):
        return message_content
    external_url = external_service_url("sns")
    data = {
        "Type": message_type,
        "MessageId": message_context.message_id,
        "TopicArn": subscriber["TopicArn"],
        "Message": message_content,
        "Timestamp": timestamp_millis(),
        "SignatureVersion": "1",
        
        
        
        "Signature": "EXAMPLEpH+..",
        "SigningCertURL": "https://sns.us-east-1.amazonaws.com/SimpleNotificationService-0000000000000000000000.pem",
    }
    if message_type == "Notification":
        unsubscribe_url = create_unsubscribe_url(external_url, subscriber["SubscriptionArn"])
        data["UnsubscribeURL"] = unsubscribe_url
    elif message_type in ("UnsubscribeConfirmation", "SubscriptionConfirmation"):
        data["Token"] = message_context.token