Update pub deps for flame 1.20 release

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pkgs/samples/lib/brick_breaker.dart
pkgs/samples/lib/default_dart.dart
pkgs/samples/lib/default_flutter.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
pkgs/samples/tool/samples.dart

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