Provide a docker-compose for the backend

[lionelhorn]

Hello, it would be nice to have a docker-compose ready to use to boostrap the postgres and redis server.

I used something along the line for my tests.

Leading to the following pg connection string postgres://root:postgres@localhost:5440/postgres

version: '3.9'
name: 'medusa-eats'

volumes:
  medusa-eats:

services:
  db:
    container_name: db
    image: postgres
    restart: always
    environment:
      POSTGRES_USER: root
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: postgres
    volumes:
      - medusa-eats:/var/lib/postgresql/data/
    ports:
      - 5440:5432
  redis:
    image: 'bitnami/redis:latest'
    environment:
      - ALLOW_EMPTY_PASSWORD=yes
    networks:
      - medusa-eats
    ports:
      - 6379:6379

networks:
  medusa-eats:
    name: medusa-eats
    external: false
  node-network:
    driver: bridge