Destination S3: Source Kafka <> Destination S3 -> Kafka 'key' field getting dropped in S3

### Connector Name

destination-s3

### Connector Version

0.4.1

### What step the error happened?

During the sync

### Revelant information

Source Kafka version used: 0.2.3
Destination S3 Version: 0.4.1
We are noticing that kafka message **key** is not getting synced in s3. Schema being replicated in S3:
**_airbyte_ab_id, _airbyte_emitted_at, value, _airbyte_additional_properties**
where value is null and record values are present in _airbyte_additional_properties

### Relevant log output

```shell
Will share logs if required - not attaching right now, since it contains sensitive data at INFO level logs - will raise a different PR to fix that
```

### Contribute

- [X] Yes, I want to contribute