Get ready for tox 4

Changes:
- eliminate whitespace in passenv values
- account for stricter allowlist checking
- removed skipsdist=True, which in tox 4 appears to prevent os-brick
  from being installed in the testenvs
- made 4.0.0 the tox minversion

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

Change-Id: I9f88d024c9d7b4f2761aa4e132ee0bd5b7272207

tox.ini

@@ -1,11 +1,12 @@
 [tox]
-minversion = 3.18.0
-skipsdist = True
-# python runtimes: https://governance.openstack.org/tc/reference/runtimes/ussuri.html
-envlist = py3,pep8
+minversion = 4.0.0
+# 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
+envlist = py3,pep8
 
 [testenv]
 basepython = python3
@@ -32,7 +33,13 @@ commands =
 
 allowlist_externals = bash
                       find
-passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
+passenv =
+    http_proxy
+    HTTP_PROXY
+    https_proxy
+    HTTPS_PROXY
+    no_proxy
+    NO_PROXY
 
 [testenv:debug]
 commands =
@@ -46,6 +53,8 @@ commands =
 
 [testenv:fast8]
 envdir = {toxworkdir}/pep8
+allowlist_externals =
+    {toxinidir}/tools/fast8.sh
 commands =
     {toxinidir}/tools/fast8.sh
 
@@ -84,13 +93,14 @@ commands =
   sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html
 allowlist_externals = rm
 
-
 [testenv:pdf-docs]
 deps = {[testenv:docs]deps}
-commands = {[testenv:docs]commands}
+commands =
+  {[testenv:docs]commands}
   sphinx-build -W -b latex doc/source doc/build/pdf
   make -C doc/build/pdf
 allowlist_externals =
+  {[testenv:docs]allowlist_externals}
   make
 
 [testenv:releasenotes]
@@ -135,8 +145,8 @@ import_exceptions = os_brick.i18n
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed
 # separately, outside of the requirements files, and develop mode disabled
-# explicitly to avoid unnecessarily installing the checked-out repo too (this
-# further relies on "tox.skipsdist = True" above).
+# explicitly to avoid unnecessarily installing the checked-out repo too
+skip_install = True
 deps = bindep
 commands = bindep {posargs}
 usedevelop = False