databases/py-sqlalchemy20: Add py-sqlalchemy20 2.0.4

The Python SQL Toolkit and Object Relational Mapper

SQLAlchemy is the Python SQL toolkit and Object Relational Mapper that gives
application developers the full power and flexibility of SQL.

It provides a full suite of well known enterprise-level persistence patterns,
designed for efficient and high-performing database access, adapted into a
simple and Pythonic domain language.