python: linter changes for pylint 3.x

python: linter changes for pylint 3.x

New bleeding edge versions, new nits to iron out. This addresses the
'check-python-tox' optional GitLab test, while 'check-python-minreqs'
saw no regressions, since it's frozen on an older version of pylint.

Fixes:
qemu/machine/machine.py:345:52: E0606: Possibly using variable 'sock' before assignment (possibly-used-before-assignment)
qemu/utils/qemu_ga_client.py:168:4: R1711: Useless return at end of function or method (useless-return)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20240626232230.408004-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>