Python dependency: Update flask-sqlalchemy requirement

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](pallets-eco/flask-sqlalchemy@3.0.0a1...3.1.1)

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

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

requirements.txt

@@ -14,7 +14,7 @@ Flask-Login==0.*
 Flask-Mail==0.*
 Flask-Migrate==4.*
 greenlet==1.1.2;  python_version <= '3.10'
-Flask-SQLAlchemy==3.0.*
+Flask-SQLAlchemy==3.1.*
 Flask-WTF==1.1.1
 Flask-Compress==1.*
 Flask-Paranoid==0.*