switch ubuntu-20.04 workflows to 24.04

[Habbie]

Short description

100% untested, let's see

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)
• checked that this code was merged to master

[Habbie]

Anyone please feel free to look at whatever is red and see if you can help. Currently it looks like the clang-format config might want some changed defaults to be made more explicit.

[omoerbeek]

Default clang-format of noble seems to be clang-format-18, while the old one is 10 or 11, I'll take a look.
I see now clang-19 is installed by the workflow, I have to check if that also updates clang-format to 19.

[omoerbeek]

This should be green now. I committed the formatting changes, causing some churn, but oh well. If we accept a little bit more churn we could remove the .clang-format change in 6fb460aab83ccee1e00f713628040643b554dc79

For people runnnig clang-format locally: switch to clang-format-19 after this is merged to avoid surprises. In general the versions of clang-format agree, but differences between versions might pop up.

[omoerbeek]

I'm ignoring the clang-tidy warnings.

[Habbie]

I'm ignoring the clang-tidy warnings.

Agreed. I'll force merge.