fix: requirements.txt to reduce vulnerabilities (#16)

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-WERKZEUG-14908843

Co-authored-by: snyk-bot <snyk-bot@snyk.io>

requirements.txt

@@ -3,3 +3,4 @@ requests>=2.32.2
 reportlab>=3.6.13
 Faker>=18.9.0
 pillow>=10.2.0 # not directly required, pinned by Snyk to avoid a vulnerability
+werkzeug>=3.1.5 # not directly required, pinned by Snyk to avoid a vulnerability