erp5_pdm: fix proxy filed

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

01:30:07

failed ERP5.UnitTest-Master

03:00:25

passed SlapOS.Eggs.UnitTest-Master.Python2

01:59:18

passed SlapOS.Eggs.UnitTest-Master.Python2

01:33:26