Compatibility backend for Python 3.7 (dev3)

This release pushes a backend package to

https://pypi.org/manage/project/flask-sqlalchemy-compat-backend-py37

for supporting the compatibility when using Python 3.7 and Flask-SQLAlchemy-compat 🔗.

This update

1. Loosen the dependency requirement of sqlalchemy from >=2.0.16 to >=2.0.0.

Full Changelog: v3.1.0.dev2-py37...v3.1.0.dev3-py37