Fix minecraft_ping for non-dict descriptions

With your recent commit, minecraft_ping now assumes that the description is a dict object. I've modified it to check if the object is a dict before using the .get method which may not exist.

Specifically, this: https://github.com/ClouDev/CloudBot/commit/45a1f65748f9722fa6f481dd149e41759424d7ea made it so that minecraft_ping will error if `data["description"]` is not a dict object. This commit adds back support for `data["description"]` being a string, without removing support for when it is a dict.