Update project howlerjs to v1.1.21

libgrabber updated project howlerjs to v1.1.21.

@goldfire

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "howlerjs",
    "repo": "goldfire/howler.js",
    "files": {
      "include": ["howler.js", "howler.min.js"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/howler.js",
    "localVersions": ["1.0.7", "1.1.7", "1.1.8", "1.1.18", "1.1.19", "1.1.20"],
    "remoteVersions": ["v1.1.0", "v1.1.1", "v1.1.2", "v1.1.3", "v1.1.4", "v1.1.5", "v1.1.6", "v1.1.7", "v1.1.8", "v1.1.9", "v1.1.10", "v1.1.11", "v1.1.12", "v1.1.13", "v1.1.14", "v1.1.15", "v1.1.16", "v1.1.17", "v1.1.18", "v1.1.19", "v1.1.20", "v1.1.21"],
    "branchVersions": []
  },
  "version": "v1.1.21",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/howler.js/1.1.21",
  "branch": "howlerjs/v1.1.21"
}
```