build(deps): bump werkzeug from 3.1.3 to 3.1.6 in /skbl

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 3.1.3 to 3.1.6.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/main/CHANGES.rst)
- [Commits](pallets/werkzeug@3.1.3...3.1.6)

---
updated-dependencies:
- dependency-name: werkzeug
  dependency-version: 3.1.6
  dependency-type: direct:production
...

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

Author: dependabot[bot]

skbl/requirements.txt

@@ -53,5 +53,5 @@ pylibmc==1.6.3
     # via skbl-portal
 pytz==2025.2
     # via flask-babel
-werkzeug==3.1.3
+werkzeug==3.1.6
     # via flask