Update the pit of the file cache

Every time a file is packaged and updated for the backend, the last version information will always be left on the user's mobile phone, and the cache must be cleared every time to display the latest version of the data. Solution: Let the backend return an updated version of the interface. Every time the frontend updates the version, it will pass the timestamp to the backend, and then the backend will judge whether it is the same as the timestamp in the library after receiving it. The same return does not need Update, if it is not the same, return to update, and then the processing method on the front end is: if you need to update, clear the cache and refresh the page.