CI: Prepare tox.ini for new tox version

CI: Prepare tox.ini for new tox version

whitelist_externals is now deprecated in favor of allowlist_externals
https://tox.wiki/en/latest/changelog.html#v4-0-0rc4-2022-12-06

space separator is no longer valid for passenv variable lists
https://tox.wiki/en/latest/changelog.html#v4-0-3-2022-12-08

Issue-ID: https://jira.linuxfoundation.org/browse/RELENG-4539
Co-authored-by: Guillaume Lambert <guillaume.lambert@orange.com>
Change-Id: If9322889b1d4625f0ddc58966adda92f614887c7
Signed-off-by: Matthew Watkins <mwatkins@linuxfoundation.org>
Signed-off-by: guillaume.lambert <guillaume.lambert@orange.com>