Fix test suite by upgrading dependencies. (#984)

* Upgrade Puppeteer to v21

* Update related dependencies; fix deprecated config.

* Fix invalid JSON.

* Fix syntax.

* Restore commented-out test to functionality.

* Bump codesandbox node version.

* More updates.

* Update CONTRIBUTING to match package.json.

CONTRIBUTING.md

@@ -5,7 +5,7 @@
 Before you can build the UV, we assume the following list of software is already installed in your system
 
 - Git
-- Node 14.18.1 or higher
+- Node 18 or higher
 - Npm 8.1.1 or higher
 
 ### Fork repository

__tests__/test.js

@@ -8,13 +8,13 @@ describe('Universal Viewer', () => {
     const title = await page.title();
     expect(title).toBe('Universal Viewer Examples');
   });
-//   it('loads the viewer images', async () => {
-//     await page.waitForSelector('#thumb0');
-//     const imageSrc = await page.$eval('#thumb0 img', e => e.src);
-//     expect(imageSrc).toEqual(
-//       expect.stringContaining(
-//         'https://iiif.wellcomecollection.org/image/b18035723_0001.JP2/full/90,/0/default.jpg?t=1620404278998'
-//       )
-//     );
-//   });
+  it('loads the viewer images', async () => {
+    await page.waitForSelector('#thumb-0');
+    const imageSrc = await page.$eval('#thumb-0 img', e => e.src);
+    expect(imageSrc).toEqual(
+      expect.stringContaining(
+        'https://iiif.wellcomecollection.org/image/b18035723_0001.JP2/full/90,/0/default.jpg'
+      )
+    );
+  });
 });