Fixing stub for wifi_radio_ping

Author: sw23

shared-bindings/wifi/Radio.c

@@ -283,7 +283,7 @@ const mp_obj_property_t wifi_radio_ap_info_obj = {
                (mp_obj_t)&mp_const_none_obj },
 };
 
-//|     def ping(self, ip: wifi.Radio, *, timeout: float = 0.5) -> float:
+//|     def ping(self, ip: ipaddress.IPv4Address, *, timeout: Optional[float] = 0.5) -> float:
 //|         """Ping an IP to test connectivity. Returns echo time in seconds.
 //|            Returns None when it times out."""
 //|         ...