title: How can I ignore certain schemas with alembic --autogenerate
body: <p>I have a library that's part of a bigger project. The library uses its own schema in a (PostgreSQL) database shared with the larger project.</p>
  
  <p>I want to use <code>alembic revision --autogenerate</code> to only generate migrations for the library's schema and ignore changes to the tables in the main/default schema. Is there any option for doing this?</p>
  
  <p>FWIW, I've tried the <code>include_schemas=False</code> parameter to context.configure in env.py, but it doesn't seem to do anything.</p>