erp5_json_form: Fix coding style

9 jobs for for_testrunner_1 in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

01:17:00

passed ERP5.CodingStyleTest-TestRunner1

00:44:45

passed ERP5.PerformanceTest-Master

00:26:01

passed ERP5.PerformanceTest-TestRunner1

00:25:58

failed ERP5.UnitTest-Master

04:02:21

failed ERP5.UnitTest-Master.Medusa

01:24:21

failed ERP5.UnitTest-TestRunner1

04:04:08

passed SlapOS.Eggs.UnitTest-Master.Python2

00:19:39

passed SlapOS.Eggs.UnitTest-Master.Python3

00:24:42