Netbox inventory: Fix NoneType issue if query_filters is not in netbox_inventory.yml (#46793)

* Added if state to refresh_url to avoid failure at NoneType when guesry_filters is undefined in netbox_inventory.yml

lib/ansible/plugins/inventory/netbox.py

@@ -352,6 +352,7 @@ class InventoryModule(BaseInventoryPlugin, Constructable):
 
     def refresh_url(self):
         query_parameters = [("limit", 0)]
+        if self.query_filters:
             query_parameters.extend(filter(lambda x: x,
                                            map(self.validate_query_parameters, self.query_filters)))
         self.device_url = self.api_endpoint + "/api/dcim/devices/" + "?" + urlencode(query_parameters)