Fix GetPriceConfigurationObserverTest product object mock

Author: thlassche

app/code/Magento/Tax/Test/Unit/Observer/GetPriceConfigurationObserverTest.php

@@ -118,7 +118,7 @@ public function testExecute($testArray, $expectedArray)
 
         $product = $this->createPartialMock(
             \Magento\Bundle\Model\Product\Type::class,
-            ['getTypeInstance', 'getTypeId', 'getStoreId', 'getSelectionsCollection']
+            ['getTypeInstance', 'getTypeId', 'getStoreId', 'getSelectionsCollection','getId']
         );
         $product->expects($this->any())
             ->method('getTypeInstance')