Bump flask-cors from 4.0.1 to 5.0.0 in /backend

Bumps [flask-cors](https://github.com/corydolphin/flask-cors) from 4.0.1 to 5.0.0.
- [Release notes](https://github.com/corydolphin/flask-cors/releases)
- [Changelog](https://github.com/corydolphin/flask-cors/blob/main/CHANGELOG.md)
- [Commits](corydolphin/flask-cors@4.0.1...5.0.0)

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

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

backend/requirements.txt

@@ -7,7 +7,7 @@ click==8.1.7
 colorama==0.4.6
 docopt==0.6.2
 Flask==3.0.3
-Flask-Cors==4.0.1
+Flask-Cors==5.0.0
 idna==3.7
 importlib-metadata==7.1.0
 itsdangerous==2.2.0