* fix: aerich migrate raises `tortoise.exceptions.FieldError` when `index.INDEX_TYPE` is not empty
* feat: add `IF NOT EXISTS` to postgres create index template
* chore: explicit declare type hints of function parameters
* feat: support `--fake` for aerich upgrade
* Add `--fake` to downgrade
* tests: check --fake result for aerich upgrade and downgrade
* Update readme
* Fix unittest failed because of `db_field_types` changed
* refactor: improve type hints and document