Now work on OSX 10.14

[fifiteen82726]

OpenWeather::Forecast.city("Cochin")
objc[1871]: +[__NSPlaceholderDictionary initialize] may have been in progress in another thread when fork() was called.
objc[1871]: +[__NSPlaceholderDictionary initialize] may have been in progress in another thread when fork() was called. We cannot safely call it or ignore it in the fork() child process. Crashing instead. Set a breakpoint on objc_initializeAfterForkError to debug.