✅(e2e) adapt e2e test to fit translation upgrade

We upgraded djangorestframework, which includes a
change in the translation system. This change caused
the e2e test for the app impress language
to fail.
To fix this, we updated the test to work
with the new translation system.

src/frontend/apps/e2e/__tests__/app-impress/language.spec.ts

@@ -131,7 +131,7 @@ test.describe('Language', () => {
     await waitForLanguageSwitch(page, TestLanguage.French);
 
     // Check for French 404 response
-    await check404Response('Pas trouvé.');
+    await check404Response('Non trouvé.');
   });
 
   test('it check translations of the slash menu when changing language', async ({