Python: Add py/request-without-cert-validation tests

Author: RasmusWL

python/ql/test/query-tests/Security/CWE-295-RequestWithoutValidation/make_request.py

@@ -32,3 +32,7 @@ def req2(verify):
 
 #Falsey value
 requests.post('https://semmle.com', verify=0) # BAD
+
+# requests treat `None` as default value, which means it is turned on
+requests.get('https://semmle.com') # OK
+requests.get('https://semmle.com', verify=None) # OK