[Bug]: GetObjectTagging does not return required TagSet

### S3Mock Version

5.2.0

### Usage Mode

Docker

### Description

Running GetObjectTagging on an object without tags returned an empty response, while an empty TagSet was expected.

https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetObjectTagging.html

### Steps to Reproduce

1. Start S3Mock
2. Create an object
3. Call GetObjectTagging

### Expected Behavior

Empty TagSet returned

### Actual Behavior

No TagSet returned

### AWS SDK

None

### Relevant Log Output

```shell

```

### Additional Context

_No response_