Cannot export Rating result

**Describe the bug**
When rating text, no result exported.

**To Reproduce**
Steps to reproduce the behavior:
1. Create a label interface using:
```

Set how likely it is that these images represent the same thing:

```
2. Annotate and export
3. Got this:
```
[
{
"text_1": "xxxxx",
"text_2": "xxxx",
"id": 556,
"annotator": 1,
"annotation_id": 7,
"created_at": "2023-08-28T03:18:13.955873Z",
"updated_at": "2023-08-28T03:20:54.839674Z",
"lead_time": 6.772
},
]
```

**Expected behavior**
The result of rating exported.

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Environment (please complete the following information):**
- OS: Mac OS 12.6
- Label Studio Version 1.8.1

**Additional context**
Add any other context about the problem here.