Update reasonable testing suite

[stucka]

On my to-do list, not sure when I'll get to it:

The warn-scraper testing suite hasn't been performing real-world testing, in some ways, in years. Nor has warn-transformer. Nor bln-python-client.

Everything is locked around old versions of Python and libraries to support them. Python 3.12 went mainstream in the Ubuntu LTS last month; Python 3.13 goes live in a month. Nothing here is testing around 3.11.

In June I started to go through and identify some possible version upgrades; this is itself now a bit out of date.

https://docs.google.com/spreadsheets/d/1NSqxIhSeCNA4Oxx-5IW5lKFxBnFUyPGp0722eZk3xQY/edit?usp=sharing

Incorporated into this perhaps should be a holistic look at what actually makes sense here. This suite until yesterday was running a pypi test that wasn't actually needed (thanks, @palewire !)

@chriszs is suggesting several pieces of the testing suite could be substituted more efficiently with one, in #623

I've been running Python 3.12 with this cluster of programs for months now, flawlessly. But changes I run with newer versions never actually get tested with them. Testing suite should reflect real-world operating conditions.

[stucka]

If ruff is not adopted bandit should be considered; bandit should also be considered for a one-off improvement run.