title: The current Dart SDK version is 2.10.4. how can I change the version into a upper version .? In a beta or dev channel
body: <p>Because classbe depends on cupertino_icons &gt;=1.0.1 which requires SDK version &gt;=2.12.0-0 &lt;3.0.0, version solving failed.
  Running &quot;flutter pub get&quot; in classbe... pub get failed (1; Because classbe depends on cupertino_icons &gt;=1.0.1 which requires SDK version &gt;</p>