Modifying the text_generation.ipynb

[tilakrayal]

https://www.tensorflow.org/text/tutorials/text_generation document is failing in the Tensorflow v2.17 which contains Keras3.0. Modified the code to the Keras2.0.

Kindly find the gist for the working code in Keras2.0.

Fixes: #75945

[review-notebook-app[bot]]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[AlaaAbbas22]

Thanks so much, I have been struggling with this for a long time! @tilakrayal