update serializers

tests/fixtures/wild/domain_redirect.yaml

@@ -1,3 +1,5 @@
+version: 1
+interactions:
 - request:
     body: null
     headers:

tests/integration/test_register_serializer.py

@@ -10,7 +10,7 @@ class MockSerializer(object):
     def deserialize(self, cassette_string):
         self.serialize_count += 1
         self.cassette_string = cassette_string
-        return []
+        return {'interactions':[]}
 
     def serialize(self, cassette_dict):
         self.deserialize_count += 1