Aiosql

- improved CI checks with `rstcheck`
- dynamic query functions point to the SQL query file
- illegal query names such as `1st` are filtered out
- documentation has been improved
- some code refactoring…

Metainformation and documentation updates.

- Improved documentation and tests.
- normalize adapter names to lowercase.

This v6.1 does:
- make very minor code and doc changes
- enhance github CI with python 3.11-dev, updated action setup and coverage

The v6.0 release:
- adds support for `pygresql` postgres driver.
- works around `pymysql` and `mysqldb` driver issues.
- adds a few more tests.
- improves the documentation, including badges which look soooo cooool.
- simplifies the development environment, CI configuration.
- updates `myproject.toml`.
- does some cleanup.

- Add Postgres adapter for `pg8000` driver.
- Add `register_adapter`.
- Use more recent CI image.
- Add `flake8` to CI.
- Update documentation.
- Update dependencies.