fix: dev-requirements.txt to reduce vulnerabilities

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

Author: snyk-bot

dev-requirements.txt

@@ -11,3 +11,4 @@ pytest-cov
 pytest-mock
 syrupy
 types-six
+requests>=2.32.4 # not directly required, pinned by Snyk to avoid a vulnerability