Adds an isbn attribute to the Product output. If an ISBN is set, it double-types the schema output to [ Product, Book ]. By double typing it, the Product can have the attributes of both schema.org/Book and schema.org/Product, and thus it can have an ISBN attribute and a price etc.
Removes the priceValidUntil attribute, as it's not sensible.
Adds a product:condition meta tag to the OpenGraph output. It defaults to new but can be filtered using the new Yoast\WP\Woocommerce\product_condition filter.
Adds a product:retailer_item_id meta tag to the OpenGraph output for Facebook Catalog usage.