chore: Final tweaks to prepare merging flame_3d (#3381)

Final tweaks to prepare merging flame_3d.

As can be seen [on the merge
PR](https://github.com/flame-engine/flame/pull/3377), we are almost
ready to have a nice diff to merge. This fixes a couple final issues:

* the `.4 -> 0.4` thing that I had copied from main before merging my
fix into main (this will "untouch" that file from the main diff)
* the min flutter version as set by `melos bs` on the flame_3d package
itself

examples/lib/stories/system/resize_example.dart

@@ -13,7 +13,7 @@ class ResizingRectangle extends RectangleComponent {
   void onGameResize(Vector2 size) {
     super.onGameResize(size);
 
-    this.size = size * .4;
+    this.size = size * 0.4;
   }
 }
 

packages/flame_3d/pubspec.yaml

@@ -9,7 +9,7 @@ funding:
 
 environment:
   sdk: ">=3.4.0 <4.0.0"
-  flutter: ">=3.22.0"
+  flutter: ">=3.24.0"
 
 dependencies:
   flame: ^1.16.0