fix(animations): change check for existings animation to pending_cancel_count field

Before it was checking `cancel_idx_counter` which is `id` counter. It
never gonna equals `0` and doesn't represent all animations that running
for that window. So it doesn't delete entry from hashmap.
That leads to bug when border and stackbar doesn't get notified after
animation ends.

komorebi/src/animation_manager.rs

@@ -99,7 +99,7 @@ impl AnimationManager {
         if let Some(animation_state) = self.animations.get_mut(&hwnd) {
             animation_state.in_progress = false;
 
-            if animation_state.cancel_idx_counter == 0 {
+            if animation_state.pending_cancel_count == 0 {
                 self.animations.remove(&hwnd);
                 ANIMATIONS_IN_PROGRESS.store(self.animations.len(), Ordering::Release);
             }