Bump werkzeug from 3.0.4 to 3.0.6 in /backend (#333)

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 3.0.4 to 3.0.6.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/main/CHANGES.rst)
- [Commits](pallets/werkzeug@3.0.4...3.0.6)

---
updated-dependencies:
- dependency-name: werkzeug
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>