merge logic fix

lib/tallty_import_export/export.rb

@@ -91,9 +91,9 @@ module TalltyImportExport
           headers.each_with_index do |header, col_index|
             _data = handle_data(record, header, index)
             if header[:merge].present? && last_row.present? && _data == last_row[col_index]
-              merge_index = merge_column_hash[col_index] || []
-              merge_index << index + first_content_row_index
-              merge_index << index + first_content_row_index + 1
+              merge_column_hash[col_index] ||= []
+              merge_column_hash[col_index] << index + first_content_row_index
+              merge_column_hash[col_index] << index + first_content_row_index + 1
             end
             row.push(_data)
           end
@@ -105,7 +105,7 @@ module TalltyImportExport
           merge_column_hash.each do |col_index, row_arr|
             split_arr(row_arr).each do |arr|
               sheet.merge_cells(
-                Axlsx::cell_r(arr.first, col_index) + ':' + Axlsx::cell_r(arr.last, col_index)
+                Axlsx::cell_r(col_index, arr.first) + ':' + Axlsx::cell_r(col_index, arr.last)
               )
             end
           end