title: Update the Android Gradle plugin to version 3.2.0 or higher / generate Flutter signed APK
body: <p>I'm developing a flutter cross-platform supporting app using Android Studio.</p>
  <p>Now I'm trying to generate signed APK for app-release but I face this following error:</p>
  <pre><code>'Generating signed Bundle requires you to update the Android Gradle plugin to version 3.2.0 or higher'.
  </code></pre>
  <p>How can I fix this? I have not a single clue..</p>
  <p>Best regards!</p>