title: Update Dart SDK from 2.10.3 to 2.12.0 in Vscode
body: <p>I am getting the following error when I try to update the environment sdk in flutter.</p>
  <blockquote>
  <p>The current Dart SDK version is 2.10.3.</p>
  </blockquote>
  <p>Because my_app requires SDK version &gt;=2.12.0 &lt;3.0.0, version solving failed.
  pub get failed (1; Because my_app requires SDK version &gt;=2.12.0 &lt;3.0.0, version solving failed.)
  exit code 1</p>
  <p><code>flutter doctor -v</code> gives me the following result</p>
  <pre><code>[✓] Flutter (Channel beta, 2.2.0, on Mac OS X 10.15.7 19H2 darwin-x64, locale en-IN)
      • Flutter version 2.2.0 at /Users/mustafazaki/flutter
      • Framework revision b22742018b (4 weeks ago), 2021-05-14 19:12:57 -0700
      • Engine revision a9d88a4d18
      • Dart version 2.13.0
  
  [✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
      • Android SDK at /Users/mustafazaki/Library/Android/sdk
      • Platform android-29, build-tools 29.0.2
      • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
      • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
      • All Android licenses accepted.
  
  [✓] Xcode - develop for iOS and macOS
      • Xcode at /Applications/Xcode.app/Contents/Developer
      • Xcode 12.1, Build version 12A7403
      • CocoaPods version 1.10.0
  
  [✓] Chrome - develop for the web
      • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
  
  [✓] Android Studio (version 4.1)
      • Android Studio at /Applications/Android Studio.app/Contents
      • Flutter plugin can be installed from:
         https://plugins.jetbrains.com/plugin/9212-flutter
      • Dart plugin can be installed from:
         https://plugins.jetbrains.com/plugin/6351-dart
      • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
  
  [✓] VS Code (version 1.56.2)
      • VS Code at /Applications/Visual Studio Code.app/Contents
      • Flutter extension version 3.23.0
  
  [✓] Connected device (3 available)
      
      • iPhone 12 Pro Max (mobile) • 67F57BF6-B6BC-4061-9BFD-01D38275C4E1 • ios            •
        com.apple.CoreSimulator.SimRuntime.iOS-14-1 (simulator)
      • Chrome (web)               • chrome                               • web-javascript • Google Chrome
        91.0.4472.77
  
  • No issues found!
  </code></pre>
  <p>Also, why I can't see the latest dart update on vscode? It shows me only 2.10.3</p>
  <p><a href="https://i.stack.imgur.com/YM7tn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YM7tn.png" alt="enter image description here" /></a></p>
  <p><code>flutter clean</code> also doesn't seem to work.</p>