@export_subgroup results in faulty formatting

## Version

0.26.1

## Godot Version

4.7.1

## Describe your issue

```gdscript
extends Resource

@export_subgroup("My subgroup")
@export var my_property: String
```

gets formatted into

```gdscript
extends Resource

@export_subgroup("My subgroup") @export var my_property: String
```

Which isn't valid GDScript.