title: Getting SQLAlchemy to issue CREATE SCHEMA on create_all
body: <p>I have a SqlAlchemy model with a schema argument like so:</p>
  <pre><code>Base = declarative_base()
  
  class Road(Base):
    __tablename__ = &quot;roads&quot;
    __table_args__ = {'schema': 'my_schema'}
    id = Column(Integer, primary_key=True)
  </code></pre>
  <p>When I use <code>Base.metadata.create_all(engine)</code> it correctly issues a <code>CREATE TABLE</code> with the schema name on the front like so <code>CREATE TABLE my_schema.roads (</code> but Postgresql rightly complains that the schema doesn't exist.</p>
  <p>Am I missing a step to get SqlAlchemy to issue the <code>CREATE SCHEMA my_schema</code> or do I have to call this manually?</p>