fix: requirements/test.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-REQUESTS-15763443

Author: snyk-bot

requirements/test.txt

@@ -8,3 +8,4 @@ moto==2.2.4
 -r exporter/gspread.txt
 -r ai/langchain.txt
 -r github_integration/github.txt
+requests>=2.33.0 # not directly required, pinned by Snyk to avoid a vulnerability