Adjust animations lint rules (#814)

animations/lib/src/basics/07_tween_sequence.dart

@@ -5,6 +5,7 @@
 import 'package:flutter/material.dart';
 
 class TweenSequenceDemo extends StatefulWidget {
+  const TweenSequenceDemo({Key? key}) : super(key: key);
   static const String routeName = '/basics/chaining_tweens';
 
   @override