### 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_
if self._should_publish(ctx.store, message, subscriber):
                        individual_ctx = SnsPublishContext(
                            message=message, store=ctx.store, request_headers=ctx.request_headers
                        )
                        LOG.debug(
                            "Topic '%s' batch publishing '%s' to subscribed '%s' with protocol '%s' (subscription '%s')",
                            topic_arn,
                            individual_ctx.message.message_id,
                            subscriber.get("Endpoint"),
                            subscriber["Protocol"],
                            subscriber["SubscriptionArn"],
                        )
                        self.executor.submit(
                            notifier.publish, context=individual_ctx, subscriber=subscriber
                        )
    def publish_to_phone_number(self, ctx: SnsPublishContext, phone_number: str) -> None:
        LOG.debug(
            "Publishing '%s' to phone number '%s' with protocol 'sms'",
            ctx.message.message_id,
            phone_number,
        )
        self.executor.submit(self.sms_notifier.publish, context=ctx, endpoint=phone_number)
    def publish_to_application_endpoint(self, ctx: SnsPublishContext, endpoint_arn: str) -> None:
        LOG.debug(
            "Publishing '%s' to application endpoint '%s'",
            ctx.message.message_id,
            endpoint_arn,
        )
        self.executor.submit(self.application_notifier.publish, context=ctx, endpoint=endpoint_arn)
    def publish_to_topic_subscriber(