PythonScript: fix Zope2 compatibility

There is no zmi_icon on Zope2.
14 jobs for fix/password_tool in 0 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

01:18:20

passed ERP5.PerformanceTest-Master

00:27:01

failed ERP5.UnitTest-Master

03:40:51

failed ERP5.UnitTest-Zope2

02:47:52

passed SlapOS.Eggs.UnitTest-Master.Python2

00:21:32

passed SlapOS.Eggs.UnitTest-Master.Python3

00:16:22

passed Wendelin.UnitTest-Master

00:35:10

passed ERP5.CodingStyleTest-Master

01:26:30

failed ERP5.PerformanceTest-Master

00:27:19

failed ERP5.UnitTest-Master

01:55:27

failed ERP5.UnitTest-Zope2

03:04:54

passed SlapOS.Eggs.UnitTest-Master.Python2

00:12:47

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:14

passed Wendelin.UnitTest-Master

00:34:44