How to configure supervisor not to kill jobs started by cron in docker container

Question

I wanted to run cron and run a few script started at a time set in crontab. I've installed cron on my docker container and wanted to add some crontab lines and cron starting in separate script. Here are fragments of my configuration

supervisord.conf

[program:cron]
command=/stats/run-crontabs.sh

/stats/run-crontabs.sh

#!/bin/bash

crontab -l | { cat; echo "11 1 * * * /stats/generate-year-rank.sh"; } | crontab -
crontab -l | { cat; echo "12 1 * * * /stats/generate-week-rank.sh"; } | crontab -
cron -f -L 15

and when it is time to run script by cron, I can see only that error in container logs

2022-01-29 01:12:01,920 INFO reaped unknown pid 691343

I wonder how I can run script by cron on docker container. Do I need supervisor?

EDIT: As @david-maze suggested I've done it like he commented and run cron as container entrypoint and problem is the same

Thank you for your help