fix: src/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

src/requirements.txt

@@ -15,4 +15,5 @@ six
 pyparsing
 pandas
 
-kivy==2.0.0rc2
+kivy==2.0.0rc2
+urllib3>=2.6.3 # not directly required, pinned by Snyk to avoid a vulnerability