Don't require Dart 3.5.

Author: lrhn

pkgs/fake_async/CHANGELOG.md

@@ -16,7 +16,6 @@
   the callback of a periodic timer would immediately invoke
   the same timer.
 * Move to `dart-lang/test` monorepo.
-* Require Dart 3.5.
 
 ## 1.3.1
 

pkgs/fake_async/pubspec.yaml

@@ -5,7 +5,7 @@ description: >-
   testing.
 repository: https://github.com/dart-lang/test/tree/master/pkgs/fake_async
 environment:
-  sdk: ^3.5.0
+  sdk: ^3.3.0
 
 dependencies:
   clock: ^1.1.0