Fix: Replace private state reference with generic State reference - somehow this change didn't make it from main (#2235)

Author: matthew-carroll

super_text_layout/example/lib/rainbow_builder.dart

@@ -12,7 +12,7 @@ class RainbowBuilder extends StatefulWidget {
   final Widget Function(BuildContext, Color) builder;
 
   @override
-  _RainbowBuilderState createState() => _RainbowBuilderState();
+  State<RainbowBuilder> createState() => _RainbowBuilderState();
 }
 
 class _RainbowBuilderState extends State<RainbowBuilder> with SingleTickerProviderStateMixin {

super_text_layout/example/lib/rainbow_character_supertext.dart

@@ -12,7 +12,7 @@ class CharacterRainbowSuperText extends StatefulWidget {
   final TextSpan text;
 
   @override
-  _CharacterRainbowSuperTextState createState() => _CharacterRainbowSuperTextState();
+  State<CharacterRainbowSuperText> createState() => _CharacterRainbowSuperTextState();
 }
 
 class _CharacterRainbowSuperTextState extends State<CharacterRainbowSuperText> with SingleTickerProviderStateMixin {
@@ -50,8 +50,8 @@ class _CharacterRainbowSuperTextState extends State<CharacterRainbowSuperText> w
               final textLength = widget.text.toPlainText().length;
               for (int i = 0; i < textLength; i += 1) {
                 // Get the bounding rectangle for the character
-                characterRects.add(textLayout.getCharacterBox(TextPosition(offset: i))?.toRect() 
-                    ?? Rect.fromLTRB(0, 0, 0, textLayout.estimatedLineHeight));
+                characterRects.add(textLayout.getCharacterBox(TextPosition(offset: i))?.toRect() ??
+                    Rect.fromLTRB(0, 0, 0, textLayout.estimatedLineHeight));
                 // Select a color for this character
                 final colorWheelDegrees =
                     ((360.0 * (characterColors.length / textLength)) + _startingColor.value) % 360;