fix classname in default sku on products table

src/Model/Table/ProductsTable.php

@@ -99,7 +99,7 @@ class ProductsTable extends Table
 
         $this->hasOne('DefaultProductSkus', [
             'foreignKey' => 'product_id',
-            'conditions' => ['PrimaryProductSkus.default_sku' => true],
+            'conditions' => ['DefaultProductSkus.default_sku' => true],
             'className' => 'CakeProducts.ProductSkus',
             'dependent' => true,
         ]);