fix: add esc_attr to session_id redirect

src/PaymentGateways/Gateways/Stripe/Traits/CheckoutRedirect.php

@@ -83,7 +83,7 @@ public static function maybeHandleRedirect()
                     // Make the id field from the Checkout Session creation API response
                     // available to this file, so you can provide it as parameter here
                     // instead of the {{CHECKOUT_SESSION_ID}} placeholder.
-                    sessionId: '<?php echo $session_id; ?>'
+                    sessionId: '<?php echo esc_attr($session_id); ?>'
                 }).then( ( result ) => {
                     console.log(result);
                     // If `redirectToCheckout` fails due to a browser or network