refactor(stock): make reservation expiration authoritative

app/Domains/Purchase/Models/Purchase.php

@@ -24,7 +24,6 @@ use Illuminate\Support\Facades\DB;
     'user_id',
     'status',
     'payment_method',
-    'expires_at',
     'total',
     'dni',
     'transfer_payer_dni',
@@ -80,7 +79,6 @@ class Purchase extends Model
             'cart_id' => 'integer',
             'stock_reservation_id' => 'integer',
             'user_id' => 'integer',
-            'expires_at' => 'datetime',
             'total' => 'decimal:2',
         ];
     }