Fix: No Notifications for checking out Consumables (#5898)

* Adds a method to consumables to check if a notification should be sent

Adds the checkin_email method to Consumables, this gets checked in notifications when checking out the consumable.

Without the method, no notifications get sent for checking out consumables.

* Fixes the checkin_email method on the License model

This should allow the License to also send checkout/checkin notifications again.

app/Models/Consumable.php

@@ -156,6 +156,10 @@ class Consumable extends SnipeModel
         return $this->belongsToMany('\App\Models\User', 'consumables_users', 'consumable_id', 'assigned_to')->count();
     }
 
+    public function checkin_email()
+    {
+        return $this->category->checkin_email;
+    }    
 
     public function requireAcceptance()
     {

app/Models/License.php

@@ -228,7 +228,7 @@ class License extends Depreciable
 
     public function checkin_email()
     {
-        return $this->model->category->checkin_email;
+        return $this->category->checkin_email;
     }
 
     public function requireAcceptance()