Bump stripe-php from 19.4.1 to 20.0.0

plugins/stripe-php/lib/version_check.php

@@ -0,0 +1,9 @@
+<?php
+
+// see: https://docs.stripe.com/sdks/versioning?lang=php
+
+if (\PHP_VERSION_ID < 70200) {
+    throw new RuntimeException(
+        'The Stripe SDK requires PHP 7.2.0 or later. You are running PHP ' . \PHP_VERSION . '.'
+    );
+}