我写了下面的代码在一个新的谷歌collabs笔记本：

!pip install --quiet --upgrade tensorflow-federated-nightly

import tensorflow as tf
import tensorflow_federated as tff

在导入tensorflow_federeated时，我收到以下错误消息：

/usr/local/lib/python3.7/dist-packages/keras/api/_v1/keras/experimental/__init__.py in <module>()
      8 from keras.feature_column.sequence_feature_column import SequenceFeatures
      9 from keras.layers.rnn.lstm_v1 import PeepholeLSTMCell
---> 10 from keras.optimizers.learning_rate_schedule import CosineDecay
     11 from keras.optimizers.learning_rate_schedule import CosineDecayRestarts
     12 from keras.premade_models.linear import LinearModel

ModuleNotFoundError: No module named 'keras.optimizers.learning_rate_schedule'; 'keras.optimizers' is not a package

这些错误似乎是从安装在colabs本身上的模块中产生的，而不是我的代码。
有什么想法可以做什么来解决这个问题？