fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-WERKZEUG-6808933

requirements.txt

@@ -11,5 +11,5 @@ pycodestyle==2.11.1
 pydocstyle==6.3.0
 requests==2.31.0
 Sphinx==7.1.2
-Werkzeug==3.0.1
+Werkzeug==3.0.3
 setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability