Install M2 version from openHAB console
bundle:uninstall org.openhab.binding.icloud
bundle:install https://openhab.jfrog.io/openhab/online-repo-milestone/2.5/org/openhab/addons/bundles/org.openhab.binding.icloud/2.5.0.M2/org.openhab.binding.icloud-2.5.0.M2.jar
Or uninstall previous one and download jar directly from link and add it to openHAB addons folder
If gson 2.8.5 lib is not installed on your environment, you can install it by following command
bundle:install http://central.maven.org/maven2/com/google/code/gson/gson/2.8.5/gson-2.8.5.jar