fix(tabs): clear slottable store properly on slotchange

.changeset/rotten-dancers-breathe.md

@@ -0,0 +1,5 @@
+---
+'@lion/tabs': patch
+---
+
+The store of invoker and content slottables was not properly cleared before repopulating, on slotchange event. This would cause duplicate entries.

packages/tabs/src/LionTabs.js

@@ -229,6 +229,7 @@ export class LionTabs extends LitElement {
     this.__store.forEach(entry => {
       cleanButton(entry);
     });
+    this.__store = [];
   }
 
   /**