First, we don't need to clone all the git repository, we only need a
sub-directory.
Secondly, as we the base_deps archives only archive the sub-directory,
subsequent run of kiwix-build in the ci will try to do a git update on
a non git repository.
By making ourselves a tar archive, we simplify the process.
The archive on download.kiwix.org has been made with :
`tar czf raspberrypy-tools.tar.gz raspberrypi-tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64`
`raspberrypi-tools` being a clone of `https://github.com/raspberrypi/tools`
commit sha is 5caa7046982f0539cf5380f94da04b31129ed521