我创建了一个flutter项目，然后运行flutter packageeages get，输出如下： [second] flutter packages get 等待另一个flutter命令释放启动锁...第二次运行“flutter packages get”...当前的Dart SDK 版本是2.0.0-dev.63.0.flutter-4c9689c1d2.
Because second depends on flutter_test any from sdk which requires SDK version <2.0.0, version solving failed.
pub get failed (1)
exit code 1
flutter doctor -v
PS D:\dartstudy\second> flutter doctor -v
[?] Flutter (Channel dev, v0.5.7, on Microsoft Windows [Version 6.1.7601], locale zh-CN)
• Flutter version 0.5.7 at E:\flutter
• Framework revision 66091f9696 (2 weeks ago), 2018-07-09 12:52:41 -0700
• Engine revision 6fe748490d
• Dart version …