modify tensorflow version on M2 chip

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In Macbook Pro M2 chip, OS 14.5 (23F79), python3.9, if use conda install -c conda-forge tensorflow=2.9.1, the specified TensorFlow version 2.9.1 may be too old for some features. Instead we recommend pip install tensorflow==2.15.0. Due to some reasons, we still need Keras and to keep its version consistent with the TensorFlow.

all dependencies related to TensorFlow as

$ pip list | grep -E '(keras|tensorflow)'      
keras                        2.15.0
tensorflow                   2.15.0
tensorflow-datasets          4.9.3
tensorflow-estimator         2.15.0
tensorflow-io-gcs-filesystem 0.37.0
tensorflow-macos             2.15.0
tensorflow-metadata          1.15.0
tensorflow-probability       0.23.0