fix: SelectableMixin should not prevent bubbling of keydown event

neither the click event nor the unselect callback is being preventing the event from bubbling, so this change simply makes the keydown event bubble up

Author: iOvergaard

packages/uui-base/lib/mixins/SelectableMixin.ts

@@ -66,7 +66,6 @@ export const SelectableMixin = <T extends Constructor<LitElement>>(
     private handleSelectKeydown(e: KeyboardEvent) {
       if (e.composedPath().indexOf(this.selectableTarget) !== -1) {
         if (e.key !== ' ' && e.key !== 'Enter') return;
-        e.preventDefault();
         this._toggleSelect();
       }
     }