feat: change attributes map to dynamic

frontend/app_flowy/packages/flowy_editor/lib/document/node.dart

@@ -1,7 +1,7 @@
 import 'dart:collection';
 import 'package:flowy_editor/document/path.dart';
 
-typedef Attributes = Map<String, Object>;
+typedef Attributes = Map<String, dynamic>;
 
 class Node extends LinkedListEntry<Node> {
   Node? parent;

frontend/app_flowy/packages/flowy_editor/lib/document/text_delta.dart

@@ -397,7 +397,7 @@ class Delta {
 Attributes? _composeMap(Attributes? a, Attributes? b) {
   a ??= {};
   b ??= {};
-  final attributes = <String, Object>{};
+  final Attributes attributes = {};
   attributes.addAll(b);
 
   for (final entry in a.entries) {