Update for Flutter 3.10 beta (#1746)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] All existing and new tests are passing.

---------

Co-authored-by: David Iglesias <ditman@gmail.com>
Co-authored-by: Mark Thompson <2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: John Ryan <ryjohn@google.com>

infinite_list/lib/main.dart

@@ -9,6 +9,7 @@ import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 import 'package:window_size/window_size.dart';
 
+import 'src/api/item.dart';
 import 'src/catalog.dart';
 import 'src/item_tile.dart';
 
@@ -78,15 +79,12 @@ class MyHomePage extends StatelessWidget {
             // to the catalog.
             var catalog = Provider.of<Catalog>(context);
 
-            // Catalog provides a single synchronous method for getting
-            // the current data.
-            var item = catalog.getByIndex(index);
-
-            if (item.isLoading) {
-              return const LoadingItemTile();
-            }
-
-            return ItemTile(item: item);
+            // Catalog provides a single synchronous method for getting the
+            // current data.
+            return switch (catalog.getByIndex(index)) {
+              Item(isLoading: true) => const LoadingItemTile(),
+              var item => ItemTile(item: item)
+            };
           },
         ),
       ),

infinite_list/pubspec.yaml

@@ -5,7 +5,7 @@ publish_to: none
 version: 1.0.0+1
 
 environment:
-  sdk: '>=2.19.5 <4.0.0'
+  sdk: ^3.0.0-0
 
 dependencies:
   flutter: