fix credit card number checker to support more lengths

store/static/js/checkout.js

@@ -51,7 +51,7 @@ checkoutForm.addEventListener("submit", (e) => {
   let exp = document.getElementById("exp");
   let cvc = document.getElementById("cvc");
 
-  var regEx = /[0-9]{16}$/;
+  var regEx = /[0-9]{8}|[0-9]{9}|[0-9]{10}|[0-9]{11}|[0-9]{12}|[0-9]{13}|[0-9]{14}|[0-9]{15}|[0-9]{16}|[0-9]{17}|[0-9]{18}|[0-9]{19}$/;
   if(number.value.replace(/\s/g, "").match(regEx)) {
       var regEx = /[0-9]{2}[/][0-9]{2}$/;
       if(exp.value.match(regEx)) {