Add 'pipeline' to UpdateByQuery whitelist (#810)

Elasticsearch Update By Query supports the pipeline parameter.  This allows the parameter to be used.

Author: feydan

src/Elasticsearch/Endpoints/UpdateByQuery.php

@@ -107,6 +107,7 @@ public function getParamWhitelist()
             'consistency',
             'scroll_size',
             'wait_for_completion',
+            'pipeline',
         ];
     }