fix: services/workshop/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-URLLIB3-10390193
- https://snyk.io/vuln/SNYK-PYTHON-URLLIB3-10390194

Author: snyk-bot

services/workshop/requirements.txt

@@ -22,3 +22,4 @@ gunicorn==21.2.0
 coverage==7.4.1
 unittest-xml-reporting==3.2.0
 black==24.4.2
+urllib3>=2.5.0 # not directly required, pinned by Snyk to avoid a vulnerability