Update poetry.lock; Remove dataclasses dependency

- Dataclasses is no longer needed. It is a dependency needed only for Python < 3.7. Realtime, however requires Python >= 3.7, and so this dep isn't needed.
  - Already removed in realtime supabase/realtime-py#48
- Fixes supabase#33 (comment) This issue comes up when using this library in AWS Lambda with serverless framework plugin serverless-python-requirements and this lock file makes it hard to deploy to Lambda with environments Python >= 3.7.

Author: ShantanuNair