Fix vulnerabilities, (replace zuul as testing lib?)

[mathiversen]

There's a lot of vulnerabilities that needs to be fixed, mostly related to zuul that hasn't been maintained for two years.

[RangerMauve]

Thanks for pointing it out. Not sure how dangerous it actually is in the current setup.

Feel free to submit a PR, but I don't think I have the bandwidth to do it any time soon. 😅