Improvements:
* Ready for Python 3.10. 828 837
* Support PyPy (with Python 3.7+). 845
Bugfixes:
* Reverse the SSL authentication mode for API requests (for Python 3.10). 836
* Update Mapping type to match new mypy (by sobolevn). 834
* Retry on `asyncio.TimeoutError` during API requests (by philipp-sontag-by). 841
Refactoring:
* Replaced `aiojobs` with a self-made fire-and-forget task orchestrator (for Python 3.10). 835