### 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_
return _client("dynamodb")
@pytest.fixture(scope="class")
def apigateway_client() -> "APIGatewayClient":
    return _client("apigateway")
@pytest.fixture(scope="class")
def iam_client() -> "IAMClient":
    return _client("iam")
@pytest.fixture(scope="class")
def s3_client() -> "S3Client":
    return _client("s3")
@pytest.fixture(scope="class")
def sqs_client() -> "SQSClient":
    return _client("sqs")
@pytest.fixture(scope="class")
def sns_client() -> "SNSClient":
    return _client("sns")
@pytest.fixture(scope="class")
def cfn_client() -> "CloudFormationClient":