remove cron.py file

cerley beat worker redis
setting for cerley

backend/dockerfile

@@ -13,6 +13,5 @@ COPY . /app/
 
 CMD ["sh", "-c", "python manage.py makemigrations && \
                    python manage.py migrate && \
-                   python manage.py crontab add && \
                    python manage.py collectstatic --no-input && \
                    gunicorn core.wsgi:application --bind 0.0.0.0:8000 --workers 3"]