mktime broken in python:3.6.14-slim?

[GeertJohan]

Celery started breaking on a call to mktime. The only thing that was changed was the base docker image.
Rolling the docker image on which the application is built back to python:3.6.13-slim fixed the issue.

I am not a python developer so I don't know exactly what is going wrong.
The error is:

OverflowError: mktime argument out of range

And it occurred on this line:
https://github.com/celery/celery/blob/v4.2.1/celery/beat.py#L259

Is this an issue with the new docker image? Time dependencies missing or broken?
Or should this be directed to the python project itself?
The python changelog says some test for mktime were fixed, and an overflow error was introduced on AIX (we're not running on AIX). https://docs.python.org/release/3.6.14/whatsnew/changelog.html#changelog

Thanks!

[wglambert]

Try using python:3.6.14-slim-buster for compatibility, the new Debian stable was released and became the default tag #633