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

Zuul is pinned to use tox < 4 in order for the py39
unit tests to pass. Additional changes for skipsdist
may be required in order to work properly with tox 4.

Partial-Bug: #2000399

Signed-off-by: Al Bailey <al.bailey@windriver.com>
Change-Id: Iab988c50b18d683a0d0967cbcc31bbad621005f8

.zuul.yaml

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

python-k8sapp-platform/k8sapp_platform/tox.ini

@@ -18,7 +18,7 @@ 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 --use-deprecated legacy-resolver \

tox.ini

@@ -15,7 +15,7 @@ setenv =
 deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
-whitelist_externals =
+allowlist_externals =
   bash
 
 [testenv:bashate]