fix: requirements/requirements_docs.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-REQUESTS-10305723

Author: snyk-bot

requirements/requirements_docs.txt

@@ -2,3 +2,4 @@ sphinx
 setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability
 urllib3>=2.2.2 # not directly required, pinned by Snyk to avoid a vulnerability
 zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability
+requests>=2.32.4 # not directly required, pinned by Snyk to avoid a vulnerability