Problem to deploy to Heroku using Docker-Compose

Question

I'm trying to deploy my code into Heroku, I’m using Docker Compose, and is getting hard to do it, I already read this link: https://devcenter.heroku.com/articles/local-development-with-docker-compose but I still have problems on how to solve it.

I have the files "docker-compose.yml" (contains Postgres DB on a volume and an application in Python (FastApi) in another volume) and "heroku.yml", but I couldn’t deploy the docker compose to Heroku.

"docker-compose.yml":

build:
  docker:
    web: ./backend/Dockerfile


version: '3.8'
services:
  server:
    build:
      context: ./backend
      dockerfile: ./Dockerfile
    volumes:
      - ./backend/:/backend/
    command: uvicorn app.main:app --proxy-headers --workers 1 --host 0.0.0.0 --port 8000
    ports:
      - "8000:8000"
    depends_on:
        - db
  db:
    image: postgres:13-alpine
    container_name: db
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    ports:
      - "5433:5432"
    environment:
      - POSTGRES_USER=****
      - POSTGRES_PASSWORD=****
      - POSTGRES_DB=****
volumes:
  postgres_data:

Thank you very much!!