fix(github): update format of labeler

Since we are using `actions/labeler@main`, its format changed, displaying the
following error with every new PR:

```
Run actions/labeler@main
The configuration file (path: .github/labeler.yml) was not found locally, fetching via the api
Error: Error: found unexpected type for label 'repository' (should be array of config options)
Error: found unexpected type for label 'repository' (should be array of config options)
```