chore(deps): bump flask from 3.1.2 to 3.1.3 in /tests/apps/python-flask

Bumps [flask](https://github.com/pallets/flask) from 3.1.2 to 3.1.3.
- [Release notes](https://github.com/pallets/flask/releases)
- [Changelog](https://github.com/pallets/flask/blob/3.1.3/CHANGES.rst)
- [Commits](https://github.com/pallets/flask/compare/3.1.2...3.1.3)

---
updated-dependencies:
- dependency-name: flask
  dependency-version: 3.1.3
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

tests/apps/python-flask/requirements.txt

@@ -1,4 +1,4 @@
-Flask==3.1.2
+Flask==3.1.3
 Jinja2==3.1.6
 Werkzeug==3.1.5
 gunicorn==25.0.2