Flutter 新手很抱歉这个问题。试图改变环境，但项目不会建立。
The current Flutter SDK version is 1.9.1+hotfix.6.
Because solemaster depends on google_sign_in >=4.0.16 which requires Flutter SDK version
>=1.10.0 <2.0.0, version solving failed.
pub get failed (1)
environment:
sdk: ">=2.1.0 <3.0.0"