Migri

Added
- Support for instantiating `PostgreSQLConnection` with an open `asyncpg` connection
- Add Python 3.10 support

Changed
- `migri` now works with `click==8*.`

Fixed
- Fix typo that prevented installing extras - e.g. `pip install migri[mysql]` now works
- Make package PEP 561 compliant

Changed
- Version to test new publish workflow

Added
- Github link in setup.py

Added
- Github workflow to build and distribute the package

Fixed
- Broken link in README badge

Added
- Add Python 3.9 support

Changed
- Update sqlparse dependency
- Redo test workflow to eliminate unstable dependency
- Add format checking to test workflow

Added
- MySQL support with [aiomysql](https://github.com/aio-libs/aiomysql)
- Dialect-specific applied_migration table initialization