Bump the pip group across 1 directory with 2 updates

Bumps the pip group with 2 updates in the /backend directory: [flask](https://github.com/pallets/flask) and [flask-cors](https://github.com/corydolphin/flask-cors).


Updates `flask` from 3.1.0 to 3.1.1
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/main/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/3.1.0...3.1.1)

Updates `flask-cors` from 5.0.0 to 6.0.0
- [Release notes](https://github.com/corydolphin/flask-cors/releases)
- [Changelog](https://github.com/corydolphin/flask-cors/blob/main/CHANGELOG.md)
- [Commits](https://github.com/corydolphin/flask-cors/compare/5.0.0...6.0.0)

---
updated-dependencies:
- dependency-name: flask
  dependency-version: 3.1.1
  dependency-type: direct:production
  dependency-group: pip
- dependency-name: flask-cors
  dependency-version: 6.0.0
  dependency-type: direct:production
  dependency-group: pip
...

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

backend/requirements.txt

@@ -1,3 +1,3 @@
-Flask==3.1.0
-Flask-CORS==5.0.0
+Flask==3.1.1
+Flask-CORS==6.0.0
 gunicorn==23.0.0