fix: SText.updateMeasuredBounds() must mutate internal bounds, not defensive copy

Closes #27

src/main/java/ovh/gasser/newshapes/shapes/SText.java

@@ -57,7 +57,7 @@ public class SText extends AbstractShape {
     }
 
     public void updateMeasuredBounds(int width, int height) {
-        getBounds().setSize(Math.max(width, 0), Math.max(height, 0));
+        bounds.setSize(Math.max(width, 0), Math.max(height, 0));
     }
 
     @Override