Fix clipping issue in YearViewSkin header

The clip for the YearViewSkin was incorrectly set to the yearView rather than the header. This change corrects the clipping to ensure the header is properly clipped according to the yearView's dimensions.

gemsfx/src/main/java/com/dlsc/gemsfx/skins/YearViewSkin.java

@@ -91,7 +91,7 @@ public YearViewSkin(YearView yearView) {
         Rectangle clip = new Rectangle();
         clip.widthProperty().bind(yearView.widthProperty());
         clip.heightProperty().bind(yearView.heightProperty());
-        yearView.setClip(clip);
+        header.setClip(clip);
 
         InvalidationListener buildGridListener = obs -> buildGrid();
         yearView.valueProperty().addListener(buildGridListener);