PEP8 linting

freqtrade/persistence.py

@@ -5,7 +5,6 @@ from sqlalchemy import Boolean, Column, DateTime, Float, Integer, String, create
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm.scoping import scoped_session
 from sqlalchemy.orm.session import sessionmaker
-from sqlalchemy.types import Enum
 
 from freqtrade import exchange