Bump flask from 3.1.2 to 3.1.3 in /python

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/main/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>

python/web/requirements.txt

@@ -5,7 +5,7 @@ blinker==1.9.0
 certifi==2026.1.4
 charset-normalizer==3.4.4
 click==8.1.8
-flask==3.1.2
+flask==3.1.3
 flask-babel==4.0.0
 idna==3.11
 importlib-metadata==8.7.1