fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-ZIPP-7430899

Author: snyk-bot

requirements.txt

@@ -3,4 +3,5 @@ BeautifulSoup4
 coverage<7.6 # manual enforcement for coveralls dependency: coveralls 1.9.2 has requirement coverage<5.0,>=3.6
 codacy-coverage
 codecov
-coveralls
+coveralls
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability