title: sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) function st_geogfromtext(unknown) does not exist
body: <p>I'm trying to create a table with geography data using geoalchemy2 with sqlalchemy following the <a href="https://geoalchemy-2.readthedocs.io/en/0.5.0/orm_tutorial.html" rel="nofollow noreferrer">geoalchemy ORM tutorial</a></p>
  
  <p>I have the postgis extension installed on the schema I'm using. The user I'm connecting with is <em>owner</em> of the schema.</p>
  
  <p><a href="https://i.stack.imgur.com/pYbkG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pYbkG.png" alt="Screenshot from pgAdmin view"></a></p>
  
  <p>When I run the python code:</p>
  
  <pre><code>from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy import Column, Integer, String
  from geoalchemy2 import Geography
  import src.config as config
  
  Base = declarative_base()
  
  class Lake(Base):
      __tablename__ = 'lake'
      __table_args__ = ({'schema': 'geobox'})
      id = Column(Integer, primary_key=True)
      country_iso_code = Column(String(2))
      zone_code = Column(String(45))
      zone_type = Column(String(45))
      zone_test = Column(Geography('POINT'))
  
  from sqlalchemy import create_engine
  engine = create_engine('postgres://{user}:{pwd}@{host}:{port}/{database}'.format(
      user=config.DbConfig().username,
      pwd=config.DbConfig().password,
      host=config.DbConfig().host,
      port=config.DbConfig().port,
      database=config.DbConfig().database), echo=True)
  
  Lake.__table__.create(engine)
  </code></pre>
  
  <p>I get the error:</p>
  
  <pre><code>sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) type "geography" does not exist
  </code></pre>
  
  <p>What am I missing here ?</p>