Correcting url used for portainer ping

main.py

@@ -90,7 +90,7 @@ class PortainerClient:
 
     def ping_server(self):
         try:
-            r = requests.get(f"{self.api_url}/", headers=self._get_headers())
+            r = requests.get(f"{self.portainer_url}/", headers=self._get_headers())
         except requests.exceptions.ConnectionError:
             return False