python3: add dependency on -compression to -core

python3: add dependency on -compression to -core

importlib.metadata is part of -core, but that will import zipfile which
is part of -compression.

Obviously this shows that our packaging of the Python modules is not
optimal.  I plan to follow up with a redesign of the splitting which
focuses on simply pulling out the larger or esoteric modules and
having a more featureful core.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>