Update flask-sqlalchemy to 2.4.0

[pyup-bot]

This PR updates flask-sqlalchemy from 2.3.2 to 2.4.0.

Changelog

2.3.3

-------------

Fix "AttributeError: 'NoneType' object has no attribute 'info'", when using polymorphic models. (`651`_)

.. _651: https://github.com/mitsuhiko/flask-sqlalchemy/pull/651

Links

• PyPI: https://pypi.org/project/flask-sqlalchemy
• Changelog: https://pyup.io/changelogs/flask-sqlalchemy/
• Repo: https://github.com/pallets/flask-sqlalchemy
• Docs: https://pythonhosted.org/Flask-SQLAlchemy/

[codecov]

Codecov Report

Merging #187 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #187   +/-   ##
=======================================
  Coverage   74.11%   74.11%           
=======================================
  Files          10       10           
  Lines         309      309           
=======================================
  Hits          229      229           
  Misses         80       80

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