flutter 引用一个shared_preferences插件，缓存一个内容，打包时报错如下：
[!] CocoaPods could not find compatible versions for pod "shared_preferences_foundation":
In Podfile:
shared_preferences_foundation (from `../myapp_flutter/.ios/.symlinks/plugins/shared_preferences_foundation/darwin`)
Specs satisfying the `shared_preferences_foundation (from `../myapp_flutter/.ios/.symlinks/plugins/shared_preferences_foundation/darwin`)` dependency were found, but they required a higher minimum deployment target.
我一个劲去改xcode工程的最低版本为12、13，一改一个不行，最后发现podfile里的版本忘改了，这两个版本都设置为iOS12即可。
