Enable Material 3 on Animations sample (#1605)

animations/lib/main.dart

@@ -178,7 +178,8 @@ class AnimationSamples extends StatelessWidget {
     return MaterialApp.router(
       title: 'Animation Samples',
       theme: ThemeData(
-        primarySwatch: Colors.deepPurple,
+        colorSchemeSeed: Colors.deepPurple,
+        useMaterial3: true,
       ),
       routerConfig: router,
     );

animations/lib/src/basics/06_custom_tween.dart

@@ -50,8 +50,7 @@ class _CustomTweenDemoState extends State<CustomTweenDemo>
       appBar: AppBar(
         title: const Text('Custom Tween'),
         actions: [
-          MaterialButton(
-            textColor: Colors.white,
+          TextButton(
             onPressed: () {
               if (controller.status == AnimationStatus.completed) {
                 controller.reverse().whenComplete(() {

animations/lib/src/misc/animated_switcher.dart

@@ -47,15 +47,11 @@ class _AnimatedSwitcherDemoState extends State<AnimatedSwitcherDemo> {
       appBar: AppBar(
         title: const Text('AnimatedSwitcher'),
         actions: [
-          MaterialButton(
+          TextButton(
             onPressed: () => setState(
               () => container = generateContainer(++keyCount),
             ),
-            child: Text(
-              'Change Widget',
-              style: TextStyle(
-                  color: Theme.of(context).buttonTheme.colorScheme!.onPrimary),
-            ),
+            child: const Text('Change Widget'),
           ),
         ],
       ),