Merge "Unpin tox"

Author: Zuul

.zuul.yaml

@@ -10,9 +10,6 @@
     # for installation.
     required-projects:
       - opendev.org/openstack/python-swiftclient
-    vars:
-      # New tox keeps breaking things as of 2023-01
-      ensure_tox_version: '<4'
 
 - job:
     name: swiftclient-functional