fix: requirements-dev.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-URLLIB3-7267250

Author: snyk-bot

requirements-dev.txt

@@ -9,3 +9,4 @@ pytest-cov
 setuptools>=65.5.1 # not directly required, pinned by Snyk to avoid a vulnerability
 sphinx
 twine<3.4
+urllib3>=2.2.2 # not directly required, pinned by Snyk to avoid a vulnerability