Update project jquery.ui-contextmenu to v1.8.1

libgrabber updated project jquery.ui-contextmenu to v1.8.1.

@mar10

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "jquery.ui-contextmenu",
    "repo": "mar10/jquery-ui-contextmenu",
    "files": {
      "include": ["jquery.ui-contextmenu.min.js", "jquery.ui-contextmenu.min.js.map"],
      "exclude": []
    },
    "path": "/home/jsdelivr/files/jquery.ui-contextmenu",
    "localVersions": ["1.6.1", "1.7.0", "1.8.0"],
    "remoteVersions": ["0.2.0", "0.3.0", "0.4.0", "0.5.0", "1.0.0", "1.1.0", "1.2.0", "1.2.2", "1.2.3", "1.2.4", "1.3.0", "v1.4.0", "v1.4.1", "v1.4.2", "v1.5.0", "v1.6.1", "v1.7.0", "v1.8.0", "v1.8.1"],
    "branchVersions": []
  },
  "version": "v1.8.1",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/jquery.ui-contextmenu/1.8.1",
  "branch": "jquery.ui-contextmenu/v1.8.1"
}
```