Make sure that the book reviews data are upto date

We show the Goodreads star count in the website. We fetch the data using the following script

`Mind-Expanding-Books/utils/update_json_files.py`

The script generates two json files which are then copied to `app/src/data` directory.

At the moment I run this script manually. But it would be cool to automate the step using GitHub actions.

The tricky thing is to make sure that you don't call the Google API(used in the script for fetching Amazon link) unnecessarily since it has a very low rate limit.

The action should only fetch the necessary data required and reuse existing data as much as it's possible.