Deit migration to Keras 3 (#2276)

* Changed initial version of APIs to keras, yet to be tested

* Migrated DEIT tutorial to keras3

* Migrated DEIT tutorial to keras3

* Added migrated by tag

* Update descriptions to reflect Keras 3 implementation

- Changed 'Last modified' date to 2026/02/10
- Updated 'TensorFlow and Keras' to just 'Keras' in Notes section
- Changed 'implementing them in TensorFlow' to 'implementing them in Keras' in Acknowledgements
- Updated 'Migrated By' to 'Converted to Keras 3 by' for clarity

* Update md file to match Keras 3 implementation

- Updated imports (removed tensorflow_addons, tensorflow_hub)
- Replaced tf.* operations with keras.ops.*
- Changed optimizer from tfa.optimizers.AdamW to keras.optimizers.AdamW
- Updated class methods to use build() with add_weight() instead of tf.Variable
- Added seed_generator to StochasticDepth class
- Added accuracy_metric to DeiT class
- Updated teacher model loading to use TFSMLayer
- Fixed preprocessing to use keras.ops.image.resize and keras.ops.one_hot
- Updated descriptions to reference Keras instead of TensorFlow

* Regenerated ipynb and md files

* Removed converted by line from md and ipynb files

Author: kharshith-k