Bump flask-sqlalchemy from 2.3.2 to 2.4.0

Bumps [flask-sqlalchemy](https://github.com/pallets/flask-sqlalchemy) from 2.3.2 to 2.4.0.
- [Release notes](https://github.com/pallets/flask-sqlalchemy/releases)
- [Changelog](https://github.com/pallets/flask-sqlalchemy/blob/master/CHANGES.rst)
- [Commits](pallets-eco/flask-sqlalchemy@2.3.2...2.4.0)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

requirements.txt

@@ -13,7 +13,7 @@ Flask-Login==0.4.0
 Flask-Mail==0.9.1
 Flask-Migrate==2.1.1
 Flask-Moment==0.5.2
-Flask-SQLAlchemy==2.3.2
+Flask-SQLAlchemy==2.4.0
 Flask-WTF==0.14.2
 guess_language-spirit==0.5.3
 idna==2.6