[BUG] compile error in Flutter 3.32.0

Run into this error when compiling project in Flutter 3.32.0:
```
../../../.pub-cache/hosted/pub.dev/flutter_html_iframe-3.0.0/lib/iframe_web.dart:33:8: Error: Undefined name 'platformViewRegistry'.
    ui.platformViewRegistry
       ^^^^^^^^^^^^^^^^^^^^
```