Address review comments

Author: Balaji Veeramani

src/sagemaker/deserializers.py

@@ -34,10 +34,8 @@ def deserialize(self, data, content_type):
         Returns:
             object: The data deserialized into an object.
         """
-        raise NotImplementedError
 
     @property
     @abc.abstractmethod
     def ACCEPT(self):
         """The content type that is expected from the inference endpoint."""
-        raise NotImplementedError

src/sagemaker/serializers.py

@@ -33,10 +33,8 @@ def serialize(self, data):
         Returns:
             object: Serialized data used for a request.
         """
-        raise NotImplementedError
 
     @property
     @abc.abstractmethod
     def CONTENT_TYPE(self):
         """The MIME type of the data sent to the inference endpoint."""
-        raise NotImplementedError