Introduce Additional Fields API for Checkout Block woocommerce/woocommerce-blocks#12073

Author: senadir

plugins/woocommerce/tests/php/src/Blocks/StoreApi/Routes/Cart.php

@@ -603,7 +603,7 @@ public function test_add_variable_product_to_cart_returns_variation_data() {
 					array(
 						'variation' => array( // order matters, alphabetical attribute order.
 							array(
-								'attribute' => 'color',
+								'attribute' => 'Color',
 								'value'     => 'red',
 							),
 							array(