FastAPI has seen a steady growth of users, as written from their site - "FastAPIis a modern, fast (high-performance), web framework for building APIs with Python 3.7+ based on standard Python type hints". And as more and more users have long running tasks which are accessed via API's in python, there is a chance they will be considering FastAPI.
This document will provide a short instruction on how to install it on your Dockerfile.
You would just need to add the package as seen below and rebuild your environment:
pip install --user "fastapi[all]"
Alternatively, you can them on your requirement.txt like the below:
After this you should be set.