Fixed wrong tax rate in price details block

The price details block will be used multiple times when rendering product listings and for every iteration, a new saleable item will be set. The getter for tax_rate is cached though and will return the same tax rate for every item in the product list, even if tax rates differ.
This fix unsets the cached tax rate after setting a new saleable item.

Block/Price/Details.php

@@ -79,6 +79,7 @@ public function __construct(
     public function setSaleableItem(\Magento\Framework\Pricing\SaleableInterface $saleableItem)
     {
         $this->saleableItem = $saleableItem;
+        $this->unsetData('tax_rate');
     }
 
     /**