v6000.1.0+1-flutter_unity_widget_2

Release 6000.1.0+1 of flutter_unity_widget_2 on pub.dev.
Works with Unity 6 and up.

+1 is for a tiny bugfix.

Changes

Includes the same changes as 2022.3.0

• [Web] Switch to package:web to support WebAssembly (WASM).
• Updates minimum supported SDK version to Flutter 3.16/Dart 3.2.
• Fix lint warnings to improve static analysis.
• Small ReadMe fixes.