ACPT-1450: fix unit tests failures

Author: vzabaznov

app/code/Magento/SalesRule/Test/Unit/Model/ValidatorTest.php

@@ -714,7 +714,7 @@ protected function setupAddressMock(
             ->getMock();
         $cartExtensionMock = $this->getMockBuilder(CartExtensionInterface::class)
             ->disableOriginalConstructor()
-            ->onlyMethods(['getShippingAssignments'])
+            ->addMethods(['getShippingAssignments'])
             ->getMockForAbstractClass();
 
         $quoteMock->method('getStore')