### 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_
Principal="sns.amazonaws.com",
            SourceArn=topic_arn,
        )
        subscription = sns_subscription(
            TopicArn=topic_arn,
            Protocol="lambda",
            Endpoint=lambda_arn,
        )
        def check_subscription():
            subscription_arn = subscription["SubscriptionArn"]
            subscription_attrs = sns_client.get_subscription_attributes(
                SubscriptionArn=subscription_arn
            )
            assert subscription_attrs["Attributes"]["PendingConfirmation"] == "false"
        retry(check_subscription, retries=PUBLICATION_RETRIES, sleep=PUBLICATION_TIMEOUT)
        sns_client.publish(TopicArn=topic_arn, Subject=subject, Message=message)
        events = retry(
            check_expected_lambda_log_events_length,
            retries=10,
            sleep=1,
            function_name=function_name,
            expected_length=1,
            regex_filter="Records.*Sns",
            logs_client=logs_client,
        )
        notification = events[0]["Records"][0]["Sns"]
        snapshot.match("notification", notification)
class TestSNSProvider:
    @pytest.mark.aws_validated
    def test_publish_unicode_chars(