Bump flask-babel from 3.1.0 to 4.0.0

Bumps [flask-babel](https://github.com/python-babel/flask-babel) from 3.1.0 to 4.0.0.
- [Release notes](https://github.com/python-babel/flask-babel/releases)
- [Changelog](https://github.com/python-babel/flask-babel/blob/master/CHANGELOG)
- [Commits](https://github.com/python-babel/flask-babel/compare/v3.1.0...v4.0.0)

---
updated-dependencies:
- dependency-name: flask-babel
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements.txt

@@ -1,6 +1,6 @@
 certifi==2023.7.22
 babel==2.13.0
-flask-babel==3.1.0
+flask-babel==4.0.0
 flask==2.3.3
 jinja2==3.1.2
 lxml==4.9.3