feat: header[:format] 关键字冲突

lib/tallty_import_export/import.rb

@@ -146,7 +146,7 @@ module TalltyImportExport
         val = header[:convert] ? send(header[:convert], v, h, info) : v
         val.strip! if val.is_a?(String)
 
-        val = handle_format(val, header, line_info)
+        val = handle_attr_type(val, header, line_info)
 
         if header[:json]
           h[header[:json]] ||= {}
@@ -168,8 +168,8 @@ module TalltyImportExport
       end.with_indifferent_access
     end
 
-    def handle_format val, header, line_info
-      case header[:format].to_s
+    def handle_attr_type val, header, line_info
+      case header[:attr_type].to_s
       when 'file'
         if val.is_a?(String)
           val = val.split("\n").map do |url|