The test on `run-examples` label application only works on PR open

### Describe the Bug

If one adds the label after opening the PR, the label doesn't run. This can be fixed by watching for events on the labels.

### To Reproduce

```python
import glass
...
```

### Expected Behaviour

_No response_

### Actual Behaviour

_No response_

### Version In Use

2025.2.dev49+geb8afba69

### Additional Context

```markdown
- Python version:
- Operating system:
```