Added DB_ECHO option for SQLAlchemy echo mode

Author: Hummer12007

gino/ext/sanic.py

@@ -119,6 +119,7 @@ async def before_server_start(_, loop):
 
             await self.set_bind(
                 dsn,
+                echo=app.config.setdefault('DB_ECHO', False),
                 min_size=app.config.setdefault('DB_POOL_MIN_SIZE', 5),
                 max_size=app.config.setdefault('DB_POOL_MAX_SIZE', 10),
                 loop=loop,