fix: update vaadin-tabsheet type to extend HTMLElement (#6939) (#6943)

Co-authored-by: Serhii Kulykov <iamkulykov@gmail.com>

packages/tabsheet/src/vaadin-tabsheet.d.ts

@@ -3,7 +3,6 @@
  * Copyright (c) 2022 Vaadin Ltd.
  * This program is available under Apache License Version 2.0, available at https://vaadin.com/license/
  */
-import { PolymerElement } from '@polymer/polymer/polymer-element.js';
 import { ControllerMixin } from '@vaadin/component-base/src/controller-mixin.js';
 import { ElementMixin } from '@vaadin/component-base/src/element-mixin.js';
 import { DelegateStateMixin } from '@vaadin/field-base/src/delegate-state-mixin.js';
@@ -70,7 +69,7 @@ export interface TabSheetEventMap extends HTMLElementEventMap, TabSheetCustomEve
  * @fires {CustomEvent} items-changed - Fired when the `items` property changes.
  * @fires {CustomEvent} selected-changed - Fired when the `selected` property changes.
  */
-declare class TabSheet extends ControllerMixin(DelegateStateMixin(ElementMixin(ThemableMixin(PolymerElement)))) {
+declare class TabSheet extends ControllerMixin(DelegateStateMixin(ElementMixin(ThemableMixin(HTMLElement)))) {
   /**
    * The index of the selected tab.
    */