Re-add stripe php library v 10.5.0, git errored because it had it's own git folder

vendor/stripe-php-10.5.0/lib/Exception/IdempotencyException.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace Stripe\Exception;
+
+/**
+ * IdempotencyException is thrown in cases where an idempotency key was used
+ * improperly.
+ */
+class IdempotencyException extends ApiErrorException
+{
+}