Drop support for Python 3.8

[Jakeroid]

Python 3.8 was released more than 5 years ago. It's already referred to as "outdated" on the official [web page](https://www.python.org/downloads/release/python-380/). The Python team will not provide any security fixes or other updates for [that release](https://www.python.org/downloads/).

It would be better to add support for Python 3.14 later.