Bump minimum tox version to 4.0
With switch of propose-translation-update nodeset to noble, tox version was bumped and whitelist_externals is no longer respected there, which leads to job failure.
Change-Id: I075b4f219501ba63d3cd2fb52f6c40e0a18fd153 Signed-off-by: Dmitriy Rabotyagov dmitriy.rabotyagov@cleura.com