fix: add extra checks for insecure_http_calls_in_python

Author: William Astorga

Splunk-TA-cisco-dnacenter/bin/cisco_dnac_api.py

@@ -189,6 +189,7 @@ def authentication_api(self, username, password):
         """
         temp_url = "/dna/system/api/v1/auth/token"
         self._endpoint_url = urllib.parse.urljoin(self._base_url, temp_url)
+        assert self._endpoint_url.startswith("https"), "URL must be HTTPS"
 
         # API request
         response = requests.post(