tox.ini started failing with tox4 which had some
incompatible changes. One of them is to allow
external command to run by adding them into allowlist_externals
and make passenv in new lines.
Fixing tox.ini for tox4 changes.
Minimal python version is now 3.8
Other minor fixes:
* Use devstack-alt-member in tests instead of devstack-alt, as
the later is having admin role now.
* Fix some of the functional tests not working anymore with the
latest mistral changes.
* Removing standard actions tests as they are not standard anymore (they
are in mistral-extra)
Change-Id: Ic0620135c286855dd4befb52eb55522b605eb863
Signed-off-by: Arnaud Morin <arnaud.morin@ovhcloud.com>