Version 8.3.0

### 8.3.0:
-   Changes
    - Firestore: Simplified the API for modifying the settings of a
      `FirebaseFirestore` instance. This is a backwards-incompatible change and
      requires updates to code that sets `FirebaseFirestore.Settings`.
    - Firestore: Changed an argument to `Query.WhereNotIn()` from `List` to
      `IEnumerable`, to be consistent with `Query.WhereIn()`.
    - Messaging (Android): Fixes an issue with receiving tokens when
      initializing the app.