4.4.0

• Increased minimum PHP version to version 8 or higher.
• Improved support for PHP 8.1 and 8.2.
• Removed usage of deprecated constant FILTER_SANITIZE_STRING.
• Added support for https://github.com/WordPress/wp-plugin-dependencies. (b8b2fd0)
• Updated manual URL to pronamicpay.com (pronamic/pronamic-pay#15). (43f1d7d)