Apply Laravel coding style

Shift automatically applies the Laravel coding style - which uses the PSR-12 coding style as a base with some minor additions.

You may customize the code style applied by configuring [Pint](https://laravel.com/docs/pint), [PHP CS Fixer](https://github.com/FriendsOfPHP/PHP-CS-Fixer), or [PHP CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer) for your project root.

For more information on customizing the code style applied by Shift, [watch this short video](https://laravelshift.com/videos/shift-code-style).

app/Models/LibraryItem.php

@@ -31,18 +31,20 @@ class LibraryItem extends Model implements HasMedia, Sortable, Feedable
 
     /**
      * The attributes that aren't mass assignable.
+     *
      * @var array
      */
     protected $guarded = [];
 
     /**
      * The attributes that should be cast to native types.
+     *
      * @var array
      */
     protected $casts = [
-        'id'          => 'integer',
+        'id' => 'integer',
         'lecturer_id' => 'integer',
-        'library_id'  => 'integer',
+        'library_id' => 'integer',
     ];
 
     public static function getFeedItems()
@@ -61,7 +63,7 @@ class LibraryItem extends Model implements HasMedia, Sortable, Feedable
     protected static function booted()
     {
         static::creating(function ($model) {
-            if (!$model->created_by) {
+            if (! $model->created_by) {
                 $model->created_by = auth()->id();
             }
         });
@@ -95,7 +97,7 @@ class LibraryItem extends Model implements HasMedia, Sortable, Feedable
         $this->addMediaCollection('single_file')
              ->acceptsMimeTypes([
                  'application/pdf', 'application/zip', 'application/octet-stream', 'application/x-zip-compressed',
-                 'multipart/x-zip'
+                 'multipart/x-zip',
              ])
              ->singleFile();
         $this->addMediaCollection('images')