Move to Flutter 3.47, use the improvements that come with this (#64)

Reviewed-on: #64

lib/controllers/multi_provider.dart

@@ -1,11 +1,10 @@
 import "dart:async";
+
 import "package:fast_immutable_collections/fast_immutable_collections.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 
-class MultiProviderController extends AsyncNotifier<void> {
-  MultiProviderController(this.providers);
-  final IList<AsyncNotifierProvider> providers;
-
+class MultiProviderController(final IList<AsyncNotifierProvider> providers)
+    extends AsyncNotifier<void> {
   @override
   Future<void> build() =>
       .wait(providers.map((provider) => ref.watch(provider.future)));