Update project underscore.string to 2.4.0

libgrabber updated project underscore.string to 2.4.0.

@epeli

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "underscore.string",
    "repo": "epeli/underscore.string",
    "files": {
      "basePath": "dist/",
      "include": ["**/*"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/underscore.string",
    "localVersions": ["2.3.1", "2.3.3"],
    "remoteVersions": ["0.9.2", "v0.9.2", "1.0.0", "v1.0.0", "v.1.1.3", "v1.1.4", "v1.1.5", "v1.1.6", "v.2.0.0", "v.2.1.1", "v.2.2.0rc", "v2.2.1", "v2.3.0", "v2.3.1", "v2.3.2", "2.3.3", "2.4.0"],
    "branchVersions": []
  },
  "version": "2.4.0",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/underscore.string/2.4.0",
  "branch": "underscore.string/2.4.0"
}
```