title: flutter pub get is stucking
body: <p>When I run in terminal <code>flutter pub get</code> is stuck  it's showing</p>
  <p>OS MacOS Catalina 10.15.3</p>
  <pre><code>Got TLS error trying to find package launch_review at https://pub.dartlang.org.                                    
  pub get failed (server unavailable) -- attempting retry 1 in 1 second...                                           
  Got socket error trying to find package launch_review at https://pub.dartlang.org.                                 
  pub get failed (server unavailable) -- attempting retry 2 in 2 seconds...                                          
  Got TLS error trying to find package launch_review at https://pub.dartlang.org.                                    
  pub get failed (server unavailable) -- attempting retry 3 in 4 seconds...                                          
  Got socket error trying to find package launch_review at https://pub.dartlang.org.                                 
  pub get failed (server unavailable) -- attempting retry 4 in 8 seconds...                                          
  Got socket error trying to find package launch_review at https://pub.dartlang.org.                              
  </code></pre>