playwright(book): let the tests pass on small screens

When the Playwright tests want to verify that the translated book
versions can be navigated to, they assumed that the links were visible,
but that is only true on "big screens". On phones, for example, the
sidebar button has to be pressed first.

With this change, a manual `npx playwright test` passes again.

Note: This was not caught by the CI runs because they only test with
Chrome (to avoid hefty downloads of the Firefox, Chromium and Webkit
browsers, only Chrome is tested because it comes pre-installed on
GitHub's hosted Actions runners).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

tests/git-scm.spec.js

@@ -228,6 +228,12 @@ test('book', async ({ page }) => {
   await expect(chaptersDropdown.locator('.active')).toHaveCount(1)
 
   // Navigate to the French translation
+  if (await page.evaluate(() => matchMedia('(max-width: 940px)').matches)) {
+    // On small screens, the links to the translated versions of the ProGit book
+    // are hidden by default, and have to be "un-hidden" by clicking on the
+    // sidebar button first.
+    await page.locator('.sidebar-btn').click();
+  }
   await page.getByRole('link', { name: 'Français' }).click()
   await expect(page).toHaveURL(/book\/fr/)
   await expect(page.getByRole('link', { name: 'Démarrage rapide' })).toBeVisible()