`ResNetRS270`, `ResNetRS350` and `ResNetRS420` model architectures. The
        ResNetRS models are based on the architecture described in
        [Revisiting ResNets: Improved Training and Scaling Strategies](https://arxiv.org/pdf/2103.07579.pdf)
    *   Added `tf.keras.optimizers.experimental.Optimizer`. The reworked
        optimizer gives more control over different phases of optimizer calls,