Release 3.47 (#2879)

Minor updates for release 3.47

## 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 have added sample code updates to the [changelog].
- [x] I updated/added relevant documentation (doc comments with `///`).


If you need help, consider asking for advice on the #hackers-devrel
channel on [Discord].

<!-- Links -->
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md
[CLA]: https://cla.developers.google.com/
[Discord]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Chat.md
[Contributors Guide]:
https://github.com/flutter/samples/blob/main/CONTRIBUTING.md
[changelog]: ../CHANGELOG.md

---------

Co-authored-by: Parker Lougheed <parlough@gmail.com>

pedometer/example/lib/main.dart

@@ -54,7 +54,7 @@ class _HomeState extends State<Home> {
     super.initState();
   }
 
-  void runPedometer() async {
+  Future<void> runPedometer() async {
     final now = DateTime.now();
     hourlySteps = await StepsRepo.instance.getSteps();
     lastUpdated = now;

pedometer/example/lib/steps_repo.dart

@@ -90,7 +90,7 @@ class _IOSStepsRepo implements StepsRepo {
       return [];
     }
 
-    final handlers = [];
+    final handlers = <ffi.Finalizable>[];
     final futures = <Future<Steps?>>[];
     final now = DateTime.now();
 
@@ -102,8 +102,8 @@ class _IOSStepsRepo implements StepsRepo {
 
       final handler = helpLib.wrapCallback(
         pd.ObjCBlock_ffiVoid_CMPedometerData_NSError.listener(lib, (
-          pd.CMPedometerData? result,
-          pd.NSError? error,
+          result,
+          error,
         ) {
           if (result != null) {
             final stepCount = result.numberOfSteps.intValue;