Fix py3 redshift encoding.

CHANGELOG.md

@@ -8,6 +8,7 @@ Latest
     * The normal @mock_<service> decorators will no longer work with boto. It is suggested that you upgrade to boto3 or use the standalone-server mode. If you would still like to use boto, you must use the @mock_<service>_deprecated decorators which will be removed in a future release.
     * The @mock_s3bucket_path decorator is now deprecated. Use the @mock_s3 decorator instead.
     * Drop support for Python 2.6
+    * Redshift server defaults to returning XML instead of JSON
 
     Added
     * Reset API: a reset API has been added to flush all of the current data ex: `requests.post("http://motoapi.amazonaws.com/moto-api/reset")`

moto/redshift/responses.py

@@ -18,7 +18,7 @@ class RedshiftResponse(BaseResponse):
             return json.dumps(response)
         else:
             xml = dicttoxml.dicttoxml(response, attr_type=False, root=False)
-            return xml
+            return xml.decode("utf-8")
 
     def create_cluster(self):
         cluster_kwargs = {