Support for `json_dumps` and `json_loads` in DjangoConnector

[maxhollmann]

I'm migrating a Django project at work from Celery to Procrastinate as a proof of concept right now, and stumbled on the lack of json_dumps and json_loads support in the Django connector. We have a lot of tasks taking datetime / date as arguments, so this would make the migration a lot simpler. I'm open to contributing a PR for this, but not sure what the best way to go about this would be. Any ideas / suggestions?

[ewjoachim]

Hello, thanks for your interest.

I have to admit that I haven't looked at this code for some time, so I'm not certain I have specifics in mind to help but feel free :)

Also, it's complicated for me to spend a lot of time on this project these days, so expect a review that might take some time (I should definitly process the PR backlog 🫣).

Good luck :)