Flutterfire: [firebase_crashlytics] runZoned with onError is deprecated in version v1.17.0

[nerder]

Describe the bug
Updating flutter to v1.17.0 (beta channel at the moment of writing) cause flutter analyze to trigger an error:

   info • 'onError' is deprecated and shouldn't be used. Use runZonedGuarded instead • lib/main.dart:73:6 • deprecated_member_use

To Reproduce
Steps to reproduce the behavior:

1. run flutter channel
2. select the channel beta
3. run flutter analyze
4. see the error in the console

Expected behavior
The example code in the documentation should not cause any deprecation warning.

[nerder]

related to https://github.com/flutter/flutter/issues/53185

[nerder]

A possible fix would be to change the documentation into something like this:

  runZonedGuarded(() {
    runApp(
      MyApp(),
    );
  }, (Object error, StackTrace stack) {
    Crashlytics.instance.recordError(error, stack);
  });