Removal of nullOk from MediaQuery.of

[BrayFlex]

Flutter is removing nullOk parameter from MediaQuery.of flutter/flutter#68736
Currently it is causing an issue for me on the newest beta branch released today.

It is on line 785 of extended_image.dart

  void _updateInvertColors() {
    _invertColors = MediaQuery.of(context, nullOk: true)?.invertColors ??
        SemanticsBinding.instance.accessibilityFeatures.invertColors;
  }

propose change to:

  void _updateInvertColors() {
    _invertColors = MediaQuery.maybeOf(context)?.invertColors ??
        SemanticsBinding.instance.accessibilityFeatures.invertColors;
  }

I've created a PR here: #264

[BrayFlex]

PR: #264

[zmtzawqlp]

#258