Fix PHP 8.4 deprecation: Implicitly marking parameter as nullable is deprecated

Hi,

I have recently migrated to PHP 8.4. I am getting a lot of deprecation warnings for this plugin:

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Helper\\DisplayManager::rule(): Implicitly marking parameter $key as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Helper/DisplayManager.php", line: 49, stack: (18)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Helper\\DCCProductStatus::clear(): Implicitly marking parameter $settings as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Helper/DCCProductStatus.php", line: 196, stack: (14)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Processor\\RefundProcessor::process(): Implicitly marking parameter $amount as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Processor/RefundProcessor.php", line: 110, stack: (12)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Helper\\PayUponInvoiceProductStatus::clear(): Implicitly marking parameter $settings as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Helper/PayUponInvoiceProductStatus.php", line: 183, stack: (8)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Settings\\SettingsListener::__construct(): Implicitly marking parameter $logger as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Settings/SettingsListener.php", line: 197, stack: (6)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Helper\\DisplayManager::rule(): Implicitly marking parameter $key as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Helper/DisplayManager.php", line: 49, stack: (18)

message: "WooCommerce\\PayPalCommerce\\WcGateway\\Helper\\DCCProductStatus::clear(): Implicitly marking parameter $settings as nullable is deprecated, the explicit nullable type must be used instead", file: "wp-content/plugins/woocommerce-paypal-payments/modules/ppcp-wc-gateway/src/Helper/DCCProductStatus.php", line: 196, stack: (14)

...

Could you please update it accordingly?

Kind regards