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

@@ -11,4 +11,5 @@ pytest-asyncio==0.23.7
 python-dotenv==1.0.1
 requests==2.32.3
 termcolor==2.4.0
-watchdog==4.0.1
+watchdog==4.0.1
+zipp>=3.19.1 # not directly required, pinned by Snyk to avoid a vulnerability