### 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_
}
    subscription.update(attributes)
    topic_subs.append(subscription)
    if subscription_arn not in sns_backend.subscription_status:
        sns_backend.subscription_status[subscription_arn] = {}
    sns_backend.subscription_status[subscription_arn].update(
        {"TopicArn": topic_arn, "Token": short_uid(), "Status": "Not Subscribed"}
    )
    
    if protocol in ["http", "https"]:
        token = short_uid()
        external_url = external_service_url("sns")
        subscription["UnsubscribeURL"] = "%s/?Action=Unsubscribe&SubscriptionArn=%s" % (
            external_url,
            subscription_arn,
        )
        confirmation = {
            "Type": ["SubscriptionConfirmation"],
            "Token": [token],
            "Message": [
                ("You have chosen to subscribe to the topic %s.\n" % topic_arn)
                + "To confirm the subscription, visit the SubscribeURL included in this message."
            ],
            "SubscribeURL": [
                "%s/?Action=ConfirmSubscription&TopicArn=%s&Token=%s"
                % (external_url, topic_arn, token)
            ],
        }
        publish_message(topic_arn, confirmation, {}, subscription_arn, skip_checks=True)
def do_unsubscribe(subscription_arn):