Fix broken main.

[polina-c]

https://github.com/dart-lang/dart-pad/actions/runs/13771805719/job/38511942985?pr=3195 :

Run dart run grinder build-project-templates
grinder running build-project-templates

build-project-templates
  flutter pub get:
    cwd: /home/runner/work/dart-pad/dart-pad/pkgs/dart_services/project_templates/dart_project
    env: {PUB_CACHE: /home/runner/work/dart-pad/dart-pad/pkgs/dart_services/local_pub_cache}
  Resolving dependencies...
  Because dartpad_sample depends on dio 5.8.0 which doesn't match any versions, version solving failed.
  
  
  You can try the following suggestion to make the pubspec resolve:
  * Try upgrading your constraint on dio: flutter pub add dio:'^5.8.0+1'
  Failed to update packages.

Bad state: pub get failed (1)
#0      ProjectCreator.buildDartProjectTemplate (package:dart_services/src/project_creator.dart:54:[7](https://github.com/dart-lang/dart-pad/actions/runs/13771805719/job/38511942985?pr=3195#step:8:8))
<asynchronous suspension>
#1      buildProjectTemplates (file:///home/runner/work/dart-pad/dart-pad/pkgs/dart_services/tool/grind.dart:90:3)
<asynchronous suspension>
#2      Grinder._invokeTask.<anon> (package:grinder/src/grinder.dart:221:24)
<asynchronous suspension>
#3      Future._kTrue (dart:async/future.dart:660:3)
<asynchronous suspension>
#4      _RootZone.bindUnaryCallbackGuarded.<anon> (dart:async/zone.dart:1[8](https://github.com/dart-lang/dart-pad/actions/runs/13771805719/job/38511942985?pr=3195#step:8:9)18:12)
<asynchronous suspension>

[github-actions]

PR Health

Breaking changes ✔️

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License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

Files
no missing headers

All source files should start with a license header.

Unrelated files missing license headers

Files
pkgs/samples/lib/brick_breaker.dart
pkgs/samples/lib/fibonacci.dart
pkgs/samples/lib/google_ai.dart
pkgs/samples/lib/hello_world.dart
pkgs/samples/lib/main.dart
pkgs/samples/lib/sunflower.dart

[devoncarew]

🎉 - thanks for getting the bots green!