Update flask-sqlalchemy requirement from <3,>=2.4 to >=2.4,<4

Updates the requirements on [flask-sqlalchemy](https://github.com/pallets-eco/flask-sqlalchemy) to permit the latest version.
- [Release notes](https://github.com/pallets-eco/flask-sqlalchemy/releases)
- [Changelog](https://github.com/pallets-eco/flask-sqlalchemy/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets-eco/flask-sqlalchemy/compare/2.4.0...3.0.0)

---
updated-dependencies:
- dependency-name: flask-sqlalchemy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

setup.cfg

@@ -32,7 +32,7 @@ install_requires =
     Flask-Mail>=0.9.1,<1
     Flask-Migrate>=2.5.3,<4  # Not following semantic versioning (e.g. https://github.com/miguelgrinberg/flask-migrate/commit/1af28ba273de6c88544623b8dc02dd539340294b)
     Flask-RESTful>=0.3.9,<1
-    Flask-SQLAlchemy>=2.4,<3
+    Flask-SQLAlchemy>=2.4,<4
     Flask-Talisman>=0.8,<2
     Flask-WTF>=0.14.3,<2
     WTForms>=2.3.1,<3.1