Update werkzeug requirement from <2.1 to <3.1 (#940)

Updates the requirements on [werkzeug](https://github.com/pallets/werkzeug) to permit the latest version.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/main/CHANGES.rst)
- [Commits](pallets/werkzeug@0.1...3.0.3)

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

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

requirements.txt

@@ -20,7 +20,7 @@ trio-typing==0.10.0
 pytest==8.2.2
 pytest-httpbin==2.0.0
 pytest-trio==0.8.0
-werkzeug<2.1  # See: https://github.com/psf/httpbin/issues/35
+werkzeug<3.1  # See: https://github.com/psf/httpbin/issues/35
 
 # Benchmarking and profiling
 uvicorn==0.30.1