Automate WooCommerce 6.1.2

* Add - Order Note Author free text field.

* Fix - Decode entities/ascii codes in email subjects.
* Fix - Introduce Newsletter block for Checkout block.
* Tweak - WC 6.2 compatibility.

* Fix - Change `changelog.txt` header format to match woorelease
* Fix - Fix/1073 opt ins emails with apostrophes not imported
* Fix - Replace is_ajax (deprecated in 6.1) with wp_doing_ajax