fix: unbreak upload retries (two bugs)

[matt-codecov]

UploadTask retries seem to be broken and i'm not sure how long ago they broke

first problem

the first problem is in tasks/base.py: celery's apply_async() function takes an options dict which may have a "headers" key. i believe it's None by default (docs aren't explicit) and as a result we attempt **None which errors with:

'NoneType' object is not a mapping

the fix for this problem is straightforward

second problem

second problem was recently introduced (by me). by changing self.retry() to self.retry(args=args, kwargs=kwargs), i excluded the repoid and commitid arguments which led to an exception in celery_task_router.py:

_get_user_plan_from_repoid() missing 1 required positional argument: 'repoid'

strangely, the clearest fix for a missing positional argument is... to add it to kwargs. regular args are not plumbed through to celery_task_router.py, and i tried to plumb them through but i just don't have the tools (read: static type system) to be confident i caught all the task operations that need to be updated.

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[giovanni-guidini]

Thanks for fixing this 🙏