[Bug]: Restart Kernel code removed from Summarize Article notebook

### File Name

gemini/tuning/sft_gemini_summarization.ipynb

### What happened?

A bug happened! In the last commit, the 'Restart Runtime in Colab' cell was removed. Due to this, when running the notebook in colab, the import libraries cell fails to run without manually restarting the runtime.

### Relevant log output

```shell

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### Code of Conduct

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