Using TensorFlow to implement the Lion optimizer, only the latest head TF11 can be used, not supporting the use of TF old versions

**Describe the feature and the current behavior/state.**
Using TensorFlow to implement the Lion optimizer, only the latest head TF11 can be used,  not supporting the use of TF old versions
The optimizer base class used is the latest TF 12, which is not supported by TF2.8.
https://github.com/google/automl/blob/master/lion/lion_tf2.py
