method to prevent linter removal of import

[dhimmel]

Nice library for essential migration functionality! You have earned my star and appreciation.

When using ruff to lint, unused imports are often removed by rule F401.

I could disable the removal with:

import alembic_postgresql_enum  # noqa: F401

It could make sense to put this # noqa: F401 comment in the readme or offer some no-op command that can be run so alembic_postgresql_enum is not deemed as unused.