Correct tox config for whitelist

tox changed the whitelist_externals to allowlist_externals
and as of tox 4.x the older name no longer works.

Change-Id: I8d5b196fc276205ede1666f0d71d0cd6550fdc22
Signed-off-by: Matt Fischer <[email protected]>

Author: matthewfischer

tox.ini

@@ -11,7 +11,7 @@ setenv =
     SYSLOG_PORT=514
     IPMI_COMMAND=External
     IPMI_CIPHER_LEVEL=17
-whitelist_externals = *
+allowlist_externals = *
 install_command = pip install {opts} {packages}
 deps = -r{toxinidir}/requirements.txt
 commands =