Read model_version details during configuration

Since https://gitlab.com/teklia/arkindex/backend/-/merge_requests/1801, the model version's details are now available on the RetrieveWorkerRun endpoint. They will prove useful for the generic workers. Store the model version configuration as model_configuration attribute on the worker.

They will be used to update the worker configuration later in the worker

if self.model_configuration:
    self.config.update(self.model_configuration)