Support tox4

Depends-On: https://review.opendev.org/866943
Change-Id: Idd5a2fdca17ae71382df68a09dfe1fc468941e14

tox.ini

@@ -1,13 +1,12 @@
 [tox]
 minversion = 3.18
 envlist = py38,pep8
-skipsdist = True
 ignore_basepython_conflict = True
 
 [testenv]
 basepython = python3
 usedevelop = True
-whitelist_externals = bash
+allowlist_externals = bash
                       find
                       rm
 setenv =
@@ -18,7 +17,7 @@ setenv =
 deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
-passenv = TEMPEST_* OS_TEST_*
+passenv = TEMPEST_*,OS_TEST_*
 commands =
   find . -type f -name "*.py[c|o]" -delete
   rm -f .testrepository/times.dbm
@@ -106,6 +105,7 @@ commands = bandit -r magnum -x tests -n5 -ll
 setenv =
   {[testenv]setenv}
   PYTHON=coverage run --source magnum --parallel-mode
+allowlist_externals = {toxinidir}/tools/cover.sh
 commands = {toxinidir}/tools/cover.sh {posargs}
 
 [testenv:docs]
@@ -118,6 +118,8 @@ commands =
 
 [testenv:pdf-docs]
 deps = {[testenv:docs]deps}
+allowlist_externals = make
+                      rm
 commands =
   rm -rf doc/build/pdf
   sphinx-build -W --keep-going -b latex -j auto doc/source doc/build/pdf