"passwd" and "pscap" are extremely useful to debug basic OS behaviour,
and tiny. So let's add them to our default development images, just to
save us some headaches.
We also add the necessary deps for ukify to the mkosi configs.
CentOS Stream 8 is dropped from CI because its python version is too
old (3.6) to be able to run ukify.
These are only needed for some kernel selftests but they prevent
building the mkosi image on aarch64 systems so let's drop them
until mkosi has support for conditional configuration so we can
only add these packages on the right architecture.
