Omit feat items blocks from txt color selector

Confirmed that the featured items WooCommerce blocks are the only Woo
blocks with a dark overlay.

By omiting them from the ruleset that sets the default text color, we
allow the block to use it's set default of white text over the
background overlay, improving color contrast.

inc/customizer/class-storefront-customizer.php

@@ -1254,7 +1254,7 @@ public function block_editor_customizer_css() {
 				/* WP <=5.3 */
 				.editor-styles-wrapper .editor-block-list__block,
 				/* WP >=5.4 */
-				.editor-styles-wrapper .block-editor-block-list__block {
+				.editor-styles-wrapper .block-editor-block-list__block:not(.wp-block-woocommerce-featured-product):not(.wp-block-woocommerce-featured-category) {
 					color: ' . $storefront_theme_mods['text_color'] . ';
 				}