zopewsgi: fixes UnboundLocalError: local variable 'warnings' referenced before assignment

91cc6c4e (ERP5Type/Utils: configure warnings in zopewsgi, 2024-02-16)
was bad, on python2 zope did not start.
5 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:39:39

failed ERP5.UnitTest-Master

01:12:40

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:17

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:32

failed Wendelin.UnitTest-Master

00:37:10