版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/upng-js/2.1.0/UPNG.js
- https://cdn.bootcdn.net/ajax/libs/upng-js/2.1.0/UPNG.min.js
- https://cdn.bootcdn.net/ajax/libs/upng-js/2.1.0/UPNG.min.js.map
Small, fast and advanced PNG / APNG encoder and decoder