fix: improve country creation logic

- Change method from find_or_create_by to find and check for nil
- Initialize a new Country object only if none exists

This fix addresses the potential issue where a country
is being unnecessarily created instead of found, improving
the efficiency of the country data synchronization process.
This change also adds clarity to the method's intent by
clearly separating the find and the initialization logic.

lib/tasks/sync_geo_data.rake

@@ -84,8 +84,9 @@ namespace :geo do
       count += 1
 
       # 查找或初始化 Country
-      country = Country.find_or_create_by(code: data["iso2"]) do |c|
-        c.name = data["name"]
+      country = Country.find_by(code: data["iso2"])
+      if country.nil?
+        country = Country.new
       end
 
       # 更新 Country 属性