This commit updates the Unix/x86 target's environment to use the latest
available LTS version of Ubuntu Linux (24.04).
Since the new OS updated some key components used in the CI build
process, a few modifications have been made to the setup and build
procedure. The new OS introduces a CPython version that is known to not
be compatible with a subset of settrace tests, so even though the OS is
updated, an older version of CPython is installed as part of the image
provisioning process.
Signed-off-by: Alessandro Gatti <a.gatti@frob.it>
21e4c036af