Check that extra params in job creation are forbidden

[javiermtorres]

What's changing

The extra=forbid model config param is passed to all OpenAPI-related models in the schema. This will prevent additional keys from being passed when creating a model object from JSON data.

How to test it

Just run auto tests; no manual testing is needed.

Additional notes for reviewers

Fixes https://github.com/mozilla-ai/lumigator/issues/393

I already...

• [x] added some tests for any new functionality
  • Existing SDK tests have been updated to comply with the schemas
• [ ] updated the documentation
  • [ ] maybe add a bullet to the schemas README?
• [x] checked if a (backend) DB migration step was required and included it if required
  • The DB models are unchanged