Add ANSIBLE_CONFIG to tox.ini

Suppress cfg-in-world-writable-dir warning in CI

tox.ini

@@ -9,6 +9,7 @@ skip_missing_interpreters=True
 [testenv]
 skip_install=True
 setenv =
+    ANSIBLE_CONFIG = ./ansible.cfg
     ANSIBLE_INVENTORY = {toxinidir}/test/tox-inventory.txt
     ANSIBLE_LOG_PATH=/tmp/tox/ansible/ansible.log
     ANSIBLE_LOCAL_TEMP=/tmp/tox/ansible