Problems with declerative_base from sqlalchemy>2.0

[FlorianK13]

Hi,

I noticed that sqlalchemy has breaking changes introduced at version 2.0.0
When running the code

from cimpyorm import datasets
db_session, model = datasets.ENTSOE_MiniBB()   

this results in the error

cimpyorm/backends.py - TypeError: declarative_base() takes 0 positional arguments but 1 was given

An easy fix would be to lock sqlalchemy at v1.4.53 in setup.py - I have tried this which results in the upper code to run sucessfully.