Use tox 4

Changes:
- eliminate whitespace in passenv values
- removed skipsdist=True, which in tox 4 appears to prevent os-brick
  from being installed in the testenvs
- made 4.4.1 the tox minversion to catch relevant bugfixes; since
  tox is not constrained, we'll actually be using the most recent
  version of tox 4
- had to adjust the functional testenv's setenv, which wasn't
  overriding OS_TEST_PATH like it did with tox 3
- used generative section names to define the various functional
  py3 testenvs we want to support locally (namely, py38, py39,
  py310, and py311)

This patch makes tox 4 the default so that we can hopefully catch
problems locally before they block the gate.

Change-Id: I01c4d44efa64650cdb46fac34a770a7aa5881baf

tox.ini

@@ -1,9 +1,10 @@
 [tox]
 distribute = False
 envlist = py3,pep8
-minversion = 3.18.0
-requires = tox<4
-skipsdist = True
+minversion = 4.4.1
+# specify virtualenv here to keep local runs consistent with the
+# gate (it sets the versions of pip, setuptools, and wheel)
+requires = virtualenv>=20.17.1
 # this allows tox to infer the base python from the environment name
 # and override any basepython configured in this file
 ignore_basepython_conflict=true
@@ -17,7 +18,9 @@ setenv =
     OS_STDOUT_CAPTURE=1
     OS_STDERR_CAPTURE=1
     OS_TEST_TIMEOUT=60
-passenv = *_proxy *_PROXY
+passenv =
+    *_proxy
+    *_PROXY
 
 deps =
        -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
@@ -83,8 +86,13 @@ deps =
   tempest>=26.0.0
 commands = stestr run {posargs}
 setenv =
-  {[testenv]setenv}
-  OS_TEST_PATH = ./cinderclient/tests/functional
+  # can't use {[testenv]setenv} here due to tox 4 issue
+  # https://github.com/tox-dev/tox/issues/2831
+  VIRTUAL_ENV={envdir}
+  OS_STDOUT_CAPTURE=1
+  OS_STDERR_CAPTURE=1
+  OS_TEST_TIMEOUT=60
+  OS_TEST_PATH=./cinderclient/tests/functional
   OS_VOLUME_API_VERSION = 3
   # must define this here so it can be inherited by the -py3* environments
   OS_CINDERCLIENT_EXEC_DIR = {envdir}/bin
@@ -99,13 +107,7 @@ setenv =
 # TLS (https) server certificate.
 passenv = OS_*
 
-[testenv:functional-py38]
-deps = {[testenv:functional]deps}
-setenv = {[testenv:functional]setenv}
-passenv = {[testenv:functional]passenv}
-commands = {[testenv:functional]commands}
-
-[testenv:functional-py39]
+[testenv:functional-py{3,38,39,310,311}]
 deps = {[testenv:functional]deps}
 setenv = {[testenv:functional]setenv}
 passenv = {[testenv:functional]passenv}
@@ -121,4 +123,3 @@ import-order-style = pep8
 [doc8]
 ignore-path=.tox,*.egg-info,doc/src/api,doc/source/drivers.rst,doc/build,.eggs/*/EGG-INFO/*.txt,doc/source/configuration/tables,./*.txt,releasenotes/build,doc/source/cli/details.rst
 extension=.txt,.rst,.inc
-