### 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_
self, ctx: SnsPublishContext, topic_arn: str, subscription_arn: str
    ) -> None:
        """
        This allows us to publish specific HTTP(S) messages specific to those endpoints, namely
        `SubscriptionConfirmation` and `UnsubscribeConfirmation`. Those are "topic" messages in shape, but are sent
        only to the endpoint subscribing or unsubscribing.
        This is only used internally.
        Note: might be needed for multi account SQS and Lambda `SubscriptionConfirmation`
        :param ctx: SnsPublishContext
        :param topic_arn: the topic of the subscriber
        :param subscription_arn: the ARN of the subscriber
        :return: None
        """
        subscriptions: List[SnsSubscription] = ctx.store.sns_subscriptions.get(topic_arn, [])
        for subscriber in subscriptions:
            if subscriber["SubscriptionArn"] == subscription_arn:
                notifier = self.topic_notifiers[subscriber["Protocol"]]
                LOG.debug(
                    "Topic '%s' publishing '%s' to subscribed '%s' with protocol '%s' (Id='%s', Subscription='%s')",
                    topic_arn,
                    ctx.message.type,
                    subscription_arn,
                    subscriber["Protocol"],
                    ctx.message.message_id,
                    subscriber.get("Endpoint"),
                )
                self.executor.submit(notifier.publish, context=ctx, subscriber=subscriber)
                return