Update tox.ini to work with tox 4

This change will allow this repo to pass zuul now
that this has merged:
https://review.opendev.org/c/zuul/zuul-jobs/+/866943

Tox 4 deprecated whitelist_externals.
Replace whitelist_externals with allowlist_externals

py39 jobs were failing due to how tox 4 skipsdist
behaves.  Therefore zuul is pinned to be < 4

Partial-Bug: #2000399

Signed-off-by: Al Bailey <al.bailey@windriver.com>
Change-Id: Ia5445a144ac7b33c811727d5846ff2f44b787ca9

.zuul.yaml

@@ -1,5 +1,7 @@
 ---
 - project:
+    vars:
+      ensure_tox_version: '<4'
     check:
       jobs:
         - openstack-tox-linters

python-k8sapp-oidc/k8sapp_oidc/tox.ini

@@ -17,7 +17,7 @@ usedevelop = True
 sitepackages = False
 
 # tox is silly... these need to be separated by a newline....
-whitelist_externals = bash
+allowlist_externals = bash
                       find
 
 install_command = pip install \

tox.ini

@@ -15,7 +15,7 @@ setenv =
 deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
-whitelist_externals =
+allowlist_externals =
   bash
 
 passenv =