Use constructor property promotion in module WeeeGraphQl

Apply suggestions from code review

Author: ihor-sviziev

app/code/Magento/WeeeGraphQl/Model/Resolver/FixedProductTax.php

@@ -26,8 +26,8 @@ class FixedProductTax implements ResolverInterface
      * @param TaxHelper $taxHelper
      */
     public function __construct(
-        private Data $weeeHelper,
-        private TaxHelper $taxHelper
+        private readonly Data $weeeHelper,
+        private readonly TaxHelper $taxHelper
     ) {
     }
 

app/code/Magento/WeeeGraphQl/Model/Resolver/Quote/FixedProductTax.php

@@ -26,8 +26,8 @@ class FixedProductTax implements ResolverInterface
      * @param TaxHelper $taxHelper
      */
     public function __construct(
-        private Data $weeeHelper,
-        private TaxHelper $taxHelper
+        private readonly Data $weeeHelper,
+        private readonly TaxHelper $taxHelper
     ) {
     }
 

app/code/Magento/WeeeGraphQl/Model/Resolver/StoreConfig.php

@@ -46,8 +46,8 @@ class StoreConfig implements ResolverInterface
      * @param TaxHelper $taxHelper
      */
     public function __construct(
-        private Data $weeeHelper,
-        private TaxHelper $taxHelper
+        private readonly Data $weeeHelper,
+        private readonly TaxHelper $taxHelper
     ) {
     }