Fix error submitting job to Flamenco

The OpenAPI changes in e561c8080e8f47b6fe792591033be4fab6faef42 did not
sit well with the generated Python code. The worker tag is now
communicated just as UUID (so that it's the same for the `SubmittedJob`
and `Job` types).

pkg/api/flamenco-openapi.yaml

@@ -1915,7 +1915,6 @@ components:
               description: >
                 If job deletion was requested, this is the timestamp at which
                 that request was stored on Flamenco Manager.
-            worker_tag: { $ref: "#/components/schemas/WorkerTag" }
           required: [id, created, updated, status, activity]
 
     JobSettings: