add a external link icon to viaf links, correct bug #27355 (https://mantis.culture.fr/mantis/view.php?id=27355)
<?php
namespace CorpusParole\Models;
use Illuminate\Database\Eloquent\Model;
class GeonamesHierarchy extends Model
{
/**
* The attributes that should be casted to native types.
*
* @var array
*/
protected $casts = [
'hierarchy' => 'array',
];
}