Add handle_format for string

lib/tallty_import_export/export.rb

@@ -174,6 +174,8 @@ module TalltyImportExport
     # 根据数据类型 attr_type 进行数据的格式化
     def handle_format data, header
       case header[:attr_type].to_s
+      when 'string'
+        date.to_s
       when 'datetime'
         data ? data.strftime('%F %H:%M') : nil
       when 'date'

lib/tallty_import_export/version.rb

 module TalltyImportExport
-  VERSION = "1.0.9"
+  VERSION = "1.0.10"
 end