Update project ractive to v0.5.6

libgrabber updated project ractive to v0.5.6.

@ractivejs

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "ractive",
    "repo": "ractivejs/ractive",
    "files": {
      "include": ["ractive-legacy.min.js", "ractive-legacy.runtime.min.js", "ractive.min.js", "ractive.runtime.min.js"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/ractive",
    "localVersions": ["0.3.9", "0.4.0", "0.5.4", "0.5.5"],
    "remoteVersions": ["v0.3.5", "v0.3.6", "v0.3.7", "v0.3.8", "v0.3.9", "v0.4.0", "v0.5.1", "v0.5.3", "v0.5.4", "v0.5.5", "v0.5.6"],
    "branchVersions": []
  },
  "version": "v0.5.6",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/ractive/0.5.6",
  "branch": "ractive/v0.5.6"
}
```