版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/css/countrySelect.css
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/css/countrySelect.min.css
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/img/flags.png
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/img/flags@2x.png
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/js/countrySelect.js
- https://cdn.bootcdn.net/ajax/libs/country-select-js/2.1.1/js/countrySelect.min.js