fix version number

Author: mariolorenz

metadata.php

@@ -60,7 +60,7 @@
         'en' => 'Use of the online payment service from amazon.com'
     ],
     'thumbnail' => 'out/img/amazon-pay-logo.png',
-    'version' => '2.1.7-rc.8',
+    'version' => '2.1.7-rc.9',
     'author' => 'OXID eSales AG',
     'url' => 'https://www.oxid-esales.com',
     'email' => 'info@oxid-esales.com',