Fix formatting for flutter-quill CI

lib/src/models/documents/nodes/container.dart

@@ -108,7 +108,9 @@ abstract class Container<T extends Node?> extends Node {
     Iterable<EmbedBuilder>? embedBuilders,
     EmbedBuilder? unknownEmbedBuilder,
   ]) =>
-      children.map((e) => e.toPlainText(embedBuilders, unknownEmbedBuilder)).join();
+      children
+      .map((e) => e.toPlainText(embedBuilders, unknownEmbedBuilder))
+      .join();
 
   /// Content length of this node's children.
   ///