کتاب خونه های فلاتر

من برای نصب کتاب خونه های فلاتر به مشکل میخورم

C:\Users\Hsein\Documents\flutter\flutter\bin\flutter.bat --no-color pub get
Waiting for another flutter command to release the startup lock...
Running "flutter pub get" in untitled4...                       
Got TLS error trying to find package shared_preferences at https://pub.dartlang.org.
pub get failed (server unavailable) -- attempting retry 1 in 1 second...
Got TLS error trying to find package shared_preferences at https://pub.dartlang.org.

من با شکن هم تست کردم نشد