WooCommerce Smart Coupons 9.18.0

* New: Credits & coupons were not getting generated & emailed when paid with [Klarna Checkout for WooCommerce](https://wordpress.org/plugins/klarna-checkout-for-woocommerce/)
* Fix: Auto apply does not happen when 'Disable email restriction?' is enabled
* Fix: Failing to add order item via AJAX that is triggered by another plugin
* Update: POT file

* Fix: When refunding an order from the refund form provided on the admin side, and in that order store credit is used, double amount is getting restored in that store credit
* Fix: When refunding an order from the refund form provided on the admin side, and in that order store credit is used, refund related meta not getting saved
* Fix: Shortcode 'smart_coupons' generating new coupons each time the page is refreshed
* Fix: 'Exclude user roles' not checking user's role when checking out as guest user
* Fix: Gift products set under 'Actions' (tab) is not getting added to cart after clicking coupon from cart, checkout page
* Fix: 'Original amount' of the store credit is not getting set when the coupon is generated either from 'Bulk generate' (tab), 'Import' (tab) or 'Send store credit' (tab)
* Fix: Uncaught exception 'Error' with message 'Call to a member function get() on null' [YITH WooCommerce Wishlist]
* Tweak: Correction in indentation as per WordPress Standards
* Tweak: Minor spelling correction
* Developer: New filter 'wc_sc_is_email_required_for_sending_coupon' to decide whether email address is required for sending coupon or not
* Update: Translation & language related changes in the template 'acknowledgement-email.php'
* Update: POT file

* Fix: Fatal error: Uncaught Error: Call to undefined function mb_detect_encoding
* Fix: When refunding an order that is paid by store credit, receiving PHP Fatal error: There has been a critical error on this website. Uncaught TypeError: gmdate(): Argument #2 ($timestamp) must be of type ?int, string given
* Update: FAQs included in the plugin
* Update: POT file