BREAKING CHANGES:
* Changed API version to v3.
* Changed OpenAPI schema.
* Dropped old bulk mechanism (now available only [`/api/endpoint/`](https://vstutils.vstconsulting.net/en/stable/backend.html#bulk-requests)).
* Squashed and removed old migrations (allowed to update only from 1.X versions).
Changelog:
* Chore: Migrate to `vstutils==5.0`.
* Feature: Provided support live update with centrifugo.
* Feature: Improved GUI performance and design.
* Feature: Provided Python 3.10 support.
* Optimization: Improved performance on `git` projects sync.
* Optimization: Used `CTE` on database for inner groups.
* Docs: Improved documentation.
* Fix: Removed useless fields on copy groups.
* Fix: Sync projects on changed origin's url.
* Fix: Twice call of `on_user_upd` hook.
* Fix: Calling old planned periodic tasks after long idling.
* Fix: Other small bugs.