♻️ Simplify DB base class declaration (#117)

* Simplify DB base class declaration

* ♻️ Remove object inheritance

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>

{{cookiecutter.project_slug}}/backend/app/app/db/base_class.py

@@ -1,11 +1,9 @@
-from sqlalchemy.ext.declarative import declarative_base, declared_attr
+from sqlalchemy.ext.declarative import as_declarative, declared_attr
 
 
-class CustomBase(object):
+@as_declarative()
+class Base:
     # Generate __tablename__ automatically
     @declared_attr
     def __tablename__(cls):
         return cls.__name__.lower()
-
-
-Base = declarative_base(cls=CustomBase)