Bhagavad-gita-api

✨ Made all endpoint functions async.
✨ Disabled GraphQL endpoints since we have created a separate GraphQL API project [in this repo](https://github.com/gita/bhagavad-gita-graphql).

Features
✨ Add docker-compose files for running the API as a docker container on the local machine as well as for deploying the API in production along with custom domain and SSL.
✨ Add composite indices to the sqlalchemy models.
✨ add `verse_order` and `slug` fields to the schemas.

Fixes
🐛 Optimize data insert scripts and delete reference scripts.
🐛 Optimize GraphQL queries.