### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

When you publish a message to SNS without a *body* (e.g. only attributes) it succeeds.

### Expected Behavior

Trying to publish a message without a *body* should fail (at least it does when trying to do this in AWS)

### How are you starting LocalStack?

Custom (please describe below)

### Steps To Reproduce

#### How are you starting localstack (e.g., `bin/localstack` command, arguments, or `docker-compose.yml`)

using Java testcontainers...

#### Client commands (e.g., AWS SDK code snippet, or sequence of "awslocal" commands)

```bash
#!/bin/sh
 
queue_arn=$(awslocal sqs create-queue --queue-name $QUEUE_NAME --output text)
echo "Queue ARN: $queue_arn"

topic_arn=$(awslocal sns create-topic --name $TOPIC_NAME --output text)
echo "Topic ARN: $topic_arn"

subscription_arn=$(awslocal sns subscribe \
    --attributes RawMessageDelivery=true \
    --topic-arn "$topic_arn" \
    --protocol sqs \
    --notification-endpoint "$queue_arn" \
    --output text)
echo "Subscription ARN: $subscription_arn" 
```


### Environment

```markdown
- OS: OSX 11.5.2
- LocalStack: 0.13.0
- Docker Desktop: v20.10.8
```


### Anything else?

_No response_
# c
        queue_name, queue_arn, queue_url = self._create_queue()
        filter_policy = {"store": [{"exists": True}]}
        def do_subscribe(self, filter_policy, queue_arn):
            self.sns_client.subscribe(
                TopicArn=self.topic_arn,
                Protocol="sqs",
                Endpoint=queue_arn,
                Attributes={"FilterPolicy": json.dumps(filter_policy)},
            )
        do_subscribe(self, filter_policy, queue_arn)
        # g
        num_msgs_0 = len(self.sqs_client.receive_message(QueueUrl=queue_url).get("Messages", []))
        # p
        message = "This is a test message"
        self.sns_client.publish(
            TopicArn=self.topic_arn,
            Message=message,
            MessageAttributes={
                "store": {"DataType": "Number", "StringValue": "99"},
                "def": {"DataType": "Number", "StringValue": "99"},
            },
        )
        def check_message1():