message: Replace add_variable() with add_weight()
  Changes in the rnn_cell.py file
diff: @@ -107,7 +107,7 @@ class TfLiteRNNCell(rnn_cell_impl.LayerRNNCell):
  input_depth = inputs_shape[-1]
  def add_variable_wrapped(name, shape, initializer, index):
  - var = self.add_variable(name, shape=shape, initializer=initializer)
  + var = self.add_weight(name, shape=shape, initializer=initializer)
  return self._tflite_wrapper.add_input(
  var, name=name, index_override=index)
  @@ -308,7 +308,7 @@ class TFLiteLSTMCell(rnn_cell_impl.LayerRNNCell):
  bias_shape = [self._num_units]
  def add_variable_wrapped(name, shape, initializer, index, partitioner):
  - var = self.add_variable(
  + var = self.add_weight(
  name, shape=shape, initializer=initializer, partitioner=partitioner)
  return self._tflite_wrapper.add_input(
  var, name=name, index_override=index)
  