feat(manifest.json): change iot_class to calculated (#59)

* feat(manifest.json): change iot_class to Calculated

The iot_class in the manifest.json file has been changed from
"cloud_polling" to "Calculated". This change is to better reflect
the nature of the IoT device's communication method.

* fix spelling

custom_components/netdaemon/manifest.json

@@ -3,7 +3,7 @@
     "@net-daemon"
   ],
   "config_flow": true,
-  "iot_class": "cloud_polling",
+  "iot_class": "calculated",
   "dependencies": [
     "http"
   ],