fix: richtext

Author: pd4d10

flutter_highlight/lib/flutter_highlight.dart

@@ -89,8 +89,8 @@ class HighlightView extends StatelessWidget {
     return Container(
       color: theme[_rootKey]?.backgroundColor ?? _defaultBackgroundColor,
       padding: padding,
-      child: SelectableText.rich(
-        TextSpan(
+      child: RichText(
+        text: TextSpan(
           style: _textStyle,
           children: _convert(highlight.parse(source, language: language).nodes),
         ),