firebase_ui_auth: widen app_links constraint to allow ^7.0.0

`firebase_ui_auth` 3.1.0 pins `app_links: ^6.4.0`. `app_links` 7.x has been out for a while (currently 7.2.1) and includes the UIScene lifecycle adoption, so any app using `firebase_ui_auth` is held on 6.4.1 and gets this on every iOS launch:

```
Plugin AppLinksIosPlugin uses deprecated application lifecycle events. Please contact plugin maintainers and request UIScene lifecycle support. This will be required in a future version of Flutter.
```

Flutter has said these warnings will become errors in a future release, so this will eventually break builds rather than just being noise.

From the app_links changelog the 6 to 7 bump looks small on the consuming side. Would you accept a PR widening the constraint to `">=6.4.0 <8.0.0"` (or straight `^7.0.0`) if the API usage in firebase_ui_auth is compatible?

Localisez la déclaration de dépendance du package firebase_ui_auth et examinez son utilisation de l’API app_links, puis comparez cette utilisation avec le changelog de app_links 7.x. Exécutez les tests existants du package et les vérifications de résolution des dépendances. C’est terminé lorsque la contrainte prise en charge accepte la version prévue de app_links sans erreurs d’API ni de build et traite l’avertissement de cycle de vie iOS signalé.

Rédigé par le modèle d'indexation à partir du texte de l'issue.