* Feature-Allow customers to choose the amount of credit to purchase.
* Tweak-Display the credit amount when a Store Credit product is added to the cart.
* Tweak-Updated the ‘Store Credit’ description text on the ‘My Account’ page.
* Tweak-Tested compatibility up to WC 6.3.
* Tweak-Tested compatibility with WP 5.9.
* Dev-Use a WC background process to handle the plugin updates.
* Dev-Use a trait instead of a class for implementing the Singleton pattern.
* Dev-Dropped deprecated plugin code up to version 3.9.
* Dev-Removed deprecated constants `WC_STORE_CREDIT_PLUS_VERSION`, `WC_STORE_CREDIT_PLUGIN_DIR`, and `WC_STORE_CREDIT_PLUGIN_URL`.
* Dev-Updated the minimum requirements to WC 3.7, WP 4.9, and PHP 5.6.