WooCommerce PDF Product Vouchers 3.12.3

* Dev - Allow third party code to toggle inclusion of variable product attributes in the product name field via `woocommerce_product_variation_title_include_attributes` filter

* Tweak - Add support for the WooCommerce Navigation admin feature

* Fix - Add sanitization to user input voucher fields to prevent HTML injection
* Fix - Ensure a variable product's variation is included in the product name field
* Fix - Ensure vouchers to generate automatically when the Checkout Block is used for checkout