Как исправить ошибку ModuleNotFoundError: No module named 'mainpage' | Django + Gunicorn + docker-compose?

FROM python:buster

ENV PYTHONUNBUFFERED 1

COPY app /app

WORKDIR /app

RUN pip install -r requirements/prod.txt

version: '3'
volumes:
  pgdata:
services: 
  web:
    build:
      context: .
      dockerfile: docker/prod/python/Dockerfile
    volumes:
        - ./app:/app
    ports: 
      - "8000:8000"
    command: gunicorn -w 4 IRMback.IRMback.wsgi.application
      - postgres
  postgres:
    image: postgres:10
    environment: 
      POSTGRES_USER: postgres
      POSTGRES_DB: postgres
      POSTGRES_PASS: admin
    volumes:
      - pgdata:/var/lib/postgresql/data
    ports:
      - 5433:5433

IRM
├── app
│   ├── backend
│   │   ├── api
│   │   ├── combinator
│   │   ├── crowler
│   │   ├── IRMback
│   │   │        ├── __init__.py
│   │   │        ├── settings.py
│   │   │        ├── urls.py
│   │   │        ├── views.py
│   │   │        ├── <b>wsgi.py</b>
│   │   ├── mainpage
│   │   ├── manage.py
│   │   └── ...
│   ├── frontend
│   │     └── ...
│   requirements
│   ├── base.txt
│   ├── local.txt
│   └── prod.txt
│   docker
│   ├── local
│             └── Dockerfile
│   ├── prod
│              └── Dockerfile
├── docker-compose.yml
└── prod.yml

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.sites',

    'rest_framework',
    'rest_framework.authtoken',
    'rest_auth',
    'allauth',
    'allauth.socialaccount',
    'allauth.socialaccount.providers.vk',
    'allauth.socialaccount.providers.google',
    'allauth.account',
    'rest_auth.registration',
    'corsheaders',

    'mainpage',
    'combinator'
]
WSGI_APPLICATION = 'IRMback.wsgi.application'