erp5_trade: fix tests

It is now needed to precompute inventories. Workflow has a new transition.
3 jobs for for-mr-pigeon in 0 seconds
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Status Job ID Name Coverage
  External
failed ERP5.Master.UnitTest-Titouan.TestRunner.Pigeon

11:12:40

failed ERP5.Master.UnitTest-Titouan.TestRunner.Pigeon

08:01:07

failed ERP5.Master.UnitTest-Titouan.TestRunner.Pigeon

04:01:00