release-by: Lanqing Huang (lqhuang)
Now you can output log to file and console simultaneously.
- Remove redundant config files
- Improve type hints
- Cleanup asyncio future utilities
- Improve code style and add an assertion
- Fix `logfile` only accepts `str` type and deprecate `sys.version` < (3, 8)
- Tune config for mypy and flake8
- Unify `setup.cfg` and `setup.py`