If using SQLAlchemy, of course the answer is Alembic[0]. But I like Alembic so much that actually, in a couple cases, I copied the model into Python/SQLAlchemy only to be able to use Alembic for migrations. Of course if you use some other ORM instead, that's a no go, but for dealing with legacy/raw DBs, it's worth the effort to have code do it for you.

[0] https://alembic.sqlalchemy.org/en/latest/