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>

experimental/pedometer/pubspec.yaml

@@ -4,7 +4,7 @@ version: 0.0.1
 publish_to: "none"
 
 environment:
-  sdk: '>=2.19.5 <4.0.0'
+  sdk: ^3.0.0-0
   flutter: ">=2.11.0"
 
 dependencies:
@@ -15,7 +15,7 @@ dependencies:
   ffi: ^2.0.1
 
 dev_dependencies:
-  ffigen: ^7.2.1
+  ffigen: ^8.0.0
   jnigen: ^0.4.0
   flutter_test:
     sdk: flutter