The corners of the time period list are not rounded

### Please answer the following questions for yourself before submitting an issue.

- [x] I checked the [knowledge base](https://adguard-vpn.com/kb/) and found no answer
- [x] I checked to make sure that this issue has not already been filed

### AdGuard VPN version

2.6.0 nightly 26 (1718)

### Environment

```markdown
- OS: Windows 11
```

### Which DNS server do you use?

Default

### Custom DNS

_No response_

### Use Wintun

- [ ] yes, I do

### Issue Details

Steps to reproduce:
1. Go to `Statistics` and click on the time period text.

### Expected Behavior

Corners should be rounded like other elements.

### Actual Behavior

The corners of the list of time period are square and not rounded.

### Screenshots

Screenshot 1


### Additional Information

_No response_