Need support for higher Kotlin Gradle version

[jijormathew]

• What went wrong:
  The Android Gradle plugin supports only Kotlin Gradle plugin version 1.5.20 and higher.
  The following dependencies do not satisfy the required version:
  project ':flutter_floatwing' -> org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.50

[ducviet321]

I'm having the same issue

[jiusanzhou]

Thank you for your reporting, I will update the version in few days later

[rorystephenson]

I've opened a PR with updated gradle config: #23.

The assistive touch panel example will not work unless you also apply the fix from #19 .

I have applied both fixes in this branch: https://github.com/rorystephenson/flutter_floatwing/tree/fix/resolve-long-cast-exception