Cleanup Master CI

update:

charmcraft.yaml for v3
tox.ini to use py3.12 by default
test-requirements.in to use zaza for juju3
update test bundles to work with charmcraft v3


generate:

merged-requirements-py312.txt
test-requirements-py312.txt


add:

update-requirements env to tox.ini and src/tox.ini


also fixes functest bundle
also fixes typo from https://review.opendev.org/q/Ib6147028ebe0bd35ebf53477909b572c8ab71398

Change-Id: I75886663c34a60ac440850a9fca81aefb04e3f28
Signed-off-by: Ioana Lazea ioana.lazea@canonical.com