Update flask-sqlalchemy requirement from ~=2.4.4 to ~=2.5.1

Updates the requirements on [flask-sqlalchemy](https://github.com/pallets/flask-sqlalchemy) to permit the latest version.
- [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@2.4.4...2.5.1)

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

Author: dependabot[bot]

requirements.txt

@@ -5,7 +5,7 @@ Flask-Gzip~=0.2
 Flask-Mail~=0.9.1
 Flask-Migrate~=2.7.0
 Flask-pyoidc~=3.7.0
-flask_sqlalchemy~=2.4.4
+flask_sqlalchemy~=2.5.1
 gunicorn~=20.0.4
 onesignal-sdk~=2.0.0
 psycopg2-binary~=2.8.6