Extend constraint on WorkerRun

Refs https://redmine.teklia.com/issues/3383

We want to support more complex typology of workflows (with multiple models with same worker version in a process):

1. introduce a new unique together constraint on WorkerRun: version + process + model_version + configuration (instead of version + process)
   • no duplicate in preprod, prod & demo: no need to manage this case (no data migration)
2. check constraint is supported cleanly in CreateWorkerRun and UpdateWorkerRun