Update project backbone.radio to v0.8.1

libgrabber updated project backbone.radio to v0.8.1.

@marionettejs

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "backbone.radio",
    "repo": "marionettejs/backbone.radio",
    "files": {
      "basePath": "build/",
      "include": ["**/*"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/backbone.radio",
    "localVersions": ["0.6.0", "0.7.0", "0.8.0"],
    "remoteVersions": ["v0.2.0", "v0.3.0", "v0.4.0", "v0.4.1", "v0.5.0", "v0.5.1", "v0.5.2", "v0.6.0", "v0.7.0", "v0.7.1", "v0.7.2", "v0.8.0", "v0.8.1"],
    "branchVersions": []
  },
  "version": "v0.8.1",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/backbone.radio/0.8.1",
  "branch": "backbone.radio/v0.8.1"
}
```