Version 13.0.0

### 13.0.0
-   Changes
    - General: Update to Firebase C++ SDK version 13.0.0.
    - General (Android): Update to Firebase Android BoM version 34.0.0.
    - General (iOS): Update to Firebase Cocoapods version 12.0.0.
    - General (iOS, tvOS): Minimum iOS and tvOS deployment target is now 15.0.
    - General: Minimum supported editor version is now Unity 2021.
    - Analytics: Removed deprecated `FirebaseAnalytics.ParameterGroupId`
      and `Parameter.Dispose` methods.
    - Auth: Removed deprecated `FirebaseUser.UpdateEmailAsync`.
    - Dynamic Links: Removed the Dynamic Links SDK. See the [support
      documentation](https://firebase.google.com/support/dynamic-links-faq)
      for more information.
    - Firebase AI: Add support for image generation via Imagen. For more info, see
      https://firebase.google.com/docs/ai-logic/generate-images-imagen
    - Firebase AI: Add support for Grounding with Google Search.
    - Firebase AI: Add support for defining a Thinking budget.
    - Firebase AI: Deprecated `CountTokensResponse.TotalBillableCharacters`, use
      `CountTokensResponse.TotalTokens` instead.
    - Firebase AI: Changed public field types for ReadOnlyMemory<byte> to byte[],
      and IEnumerable to IReadOnlyList.
    - Messaging: Removed deprecated `FirebaseMessage.Dispose`,
      `FirebaseNotification.Dispose`, and `MessagingOptions.Dispose` methods.