test: add testing-library/dom and jquery dependencies

[afc163]

 FAIL  examples/__tests__/CentreMode.test.js
  ● Test suite failed to run

    Cannot find module '@testing-library/dom' from 'node_modules/_@testing-library_react@16.3.0@@testing-library/react/dist/pure.js'

    Require stack:
      node_modules/_@testing-library_react@16.3.0@@testing-library/react/dist/pure.js
      node_modules/_@testing-library_react@16.3.0@@testing-library/react/dist/index.js
      examples/__tests__/CentreMode.test.js

      1 | import React from "react";
      2 | import CenterMode from "../CenterMode";
    > 3 | import { render } from "@testing-library/react";
        | ^
      4 | import { html as beautify_html } from "js-beautify";
      5 | import {
      6 |   getActiveSlides,

 FAIL  __tests__/SimpleSlider.test.js
  ● Test suite failed to run

    Cannot find module 'jquery' from '__tests__/testUtils.js'

    Require stack:
      __tests__/testUtils.js
      __tests__/SimpleSlider.test.js

      1 | import React from "react";
    > 2 | import $ from "jquery";
        | ^
      3 | import assign from "object-assign";
      4 | import { render } from "@testing-library/react";
      5 | import Slider from "../src/slider";

      at Resolver._throwModNotFoundError (node_modules/_jest-resolve@28.1.3@jest-resolve/build/resolver.js:491:11)
      at Object.require (__tests__/testUtils.js:2:1)
      at Object.require (__tests__/SimpleSlider.test.js:3:1)