1.flutter github地址
https://github.com/flutter/flutter
2.flutter 版本升级
https://flutterchina.club/upgrading/
flutter upgrade 更新Flutter SDK和你的依赖包
flutter packages get获取pubspec.yaml文件中列出的所有依赖包
flutter packages upgrade 获取pubspec.yaml文件中列出的所有依赖包的最新版本
3.分支管理：
查看当前分支：flutter channel
切换分支：flutter channel master
4.版本升级遇到一些问题
fatal: early EOF
fatal: The remote end hung up unexpectedly
fatal: index-pack failed
error: RPC failed; curl 18 transfer closed with outstanding read data remaining
fatal: unable to access 'https://github.com/flutter/flutter.git/': SSL read: error:00000000:lib(0):func(0):reason(0), errno 10054
解决：git config --global http.postBuffer 1073741824
curl 56 OpenSSL SSL_read:SSL_ERROR_sysCALL
解决：git config http.sslVerify "false"
