feat: options ** 时 symbolize_keys

lib/tallty_import_export/import.rb

@@ -106,7 +106,7 @@ module TalltyImportExport
 
     def process_options(options)
       options = import_options.merge(options).with_indifferent_access
-      @headers = options.delete(:headers) || import_headers(**options)
+      @headers = options.delete(:headers) || import_headers(**options.symbolize_keys)
       @primary_keys = options.delete(:primary_keys) || @headers.map { |header| header[:primary_key] ? header[:key].to_sym : nil }.compact
       @skip_keys = options.delete(:skip_keys) || @headers.map { |header| header[:skip] ? header[:key].to_sym : nil }.compact
       @params = options