title: Dart SDK version mismatch while installing build_runner
body: <p>I'm trying to add <code>build_runner: ^1.10.2</code> to <code>dev_dependencies</code> in the <code>pubspec.yaml</code> file, but I am getting the following error:</p>
  <pre class="lang-none prettyprint-override"><code>The current Dart SDK version is 2.9.0.
  
  Because project_name depends on build_runner &gt;=1.10.2 which requires SDK version &gt;=2.10.0-0.0 &lt;3.0.0, version solving failed.
  pub get failed (1; Because project_name depends on build_runner &gt;=1.10.2 which requires SDK version &gt;=2.10.0-0.0 &lt;3.0.0, version solving failed.)
  </code></pre>
  <p>I checked the dart website and the latest version of Dart SDK is 2.9.0 while 2.10 is still in dev.</p>
  <p>Here's my <code>flutter doctor</code> output:</p>
  <pre class="lang-none prettyprint-override"><code>Doctor summary (to see all details, run flutter doctor -v):
  [√] Flutter (Channel stable, 1.20.1, on Microsoft Windows [Version 10.0.18362.959], locale en-IN)
  
  [√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
  [√] Android Studio (version 4.0)
  [√] VS Code, 64-bit edition (version 1.39.2)
  [√] Connected device (1 available)
  
  • No issues found!
  
  </code></pre>