deps: update python version in container image

[hegerdes]

I just noticed that the container image is still based on python 3.8 which became end of life 4 months ago. Is it possible to update to python 3.11 or 3.12?

Since the app has minimal dependencies it should not be a problem. At least I did not encounter any in my quick test with v3.11.

If I can help any way, like with a PR I would happly do so.

Just for reference the current python support martix