panel: Fix panel to unexpected size chagnes when moved some panel. (#506)

### Before 



https://github.com/user-attachments/assets/9174033b-d901-412f-9176-cdef6438822f

crates/ui/src/resizable/panel.rs

@@ -338,6 +338,7 @@ impl ResizablePanel {
     fn update_size(&mut self, bounds: Bounds<Pixels>, cx: &mut ViewContext<Self>) {
         let new_size = bounds.size.along(self.axis);
         self.bounds = bounds;
+        self.size_ratio = None;
         self.size = Some(new_size);
 
         let entity_id = cx.view().entity_id();