chore: Enable DCM rule double-literal-format (#3248)

Enable DCM rule double-literal-format.

More details
[here](https://dcm.dev/docs/rules/common/double-literal-format/). This
both forbids trailing zeroes and mandates leading zeroes.

If we would prefer a different style (e.g. prefer no leading zero
instead), just lmk :)

packages/flame_network_assets/example/lib/main.dart

@@ -31,7 +31,7 @@ class MyGame extends FlameGame with TapDetector {
         SpriteAnimationData.sequenced(
           textureSize: Vector2(48, 32),
           amount: 4,
-          stepTime: .2,
+          stepTime: 0.2,
         ),
         size: Vector2(100, 50),
         anchor: Anchor.center,