WaniKani commands no longer work due to deprecation of WaniKani API V1

WaniKani recently deprecated the API that Sigma was using to support the >>wanikani command.

https://community.wanikani.com/t/we-salute-you-api-version-1/45715

As such, it no longer works. Even if the user uses >>wanikanisave to update their API key to a API Version 2 key, the command still does not work. Sigma's >>wanikani command will have to be updated to use API Version 2 instead.