fix: access city attribute correctly in WeatherArt model

- Modified the formatted_time method to use 'self' when accessing the city attribute
- This change fixes a bug where the city attribute was not being accessed correctly, ensuring proper timezone information retrieval.

app/models/weather_art.rb

@@ -70,7 +70,7 @@ class WeatherArt < ApplicationRecord
 
   def formatted_time(type = :date, use_local_timezone = false)
     # 获取时区
-    timezone_info = city&.country&.timezones.present? ?
+    timezone_info = self.city&.country&.timezones.present? ?
                       eval(self.city.country.timezones).first :
                       { "zoneName" => "UTC", "gmtOffsetName" => "UTC+00:00" }