Change date of CityForecast to datetime

lib/weather-model/source_schemas/forecast.rb

@@ -15,7 +15,7 @@ module WeatherModel
           win_speed: :string,
         },
         options: {
-          index: [:cityname, :date],
+          index: [:cityname, :datetime],
           expire: 11 * 24 * 60 * 60,
           unique: nil,
           belongs_to: nil,