docs: add fastapi-sqla to ORM section

[hadrien]

Added Fastapi-SQLA to the list in the ORM section in alphabetical order.

Why is it awesome?

1. It support latest SQLAlchemy development and best practices: asyncio support, 2.0 syntax, session guidelines;
2. It provides pagination support out-of-the box;
3. It provides pytest fixtures;
4. It uses Fastapi dependency injection & starlette middleware;
5. It is carefully maintained and the team is super responsive and diligent whenever someone opens an issue;