SQLite3 does not generate classes，（python 3.8.1 sqlite 3.2.5) #34
Description
command line:
flask-sqlacodegen --flask sqlite:///data.db --outfile models_gen.py
gen result:
coding: utf-8
from sqlalchemy import Column, Integer, Table, Text
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
t_user_info = db.Table(
'user_info',
db.Column('id', db.Integer),
db.Column('reg_init_date', db.Text),
db.Column('lease_expiration', db.Text),
db.Column('strdogsoftid', db.Text),
db.Column('reg_user_name', db.Text),
db.Column('function_version', db.Integer),
db.Column('type_version', db.Integer)
)