fix: Who-Is/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-URLLIB3-14896210

Author: snyk-bot

Who-Is/requirements.txt

@@ -1,2 +1,3 @@
 netaddr==0.7.18
-requests==2.31.0
+requests==2.31.0
+urllib3>=2.6.3 # not directly required, pinned by Snyk to avoid a vulnerability