Version 8.5.0

### 8.5.0:
-   Changes
    - General (iOS): iOS SDKs are now built using Xcode 13.0.0.
    - Crashlytics: Improved crash reporting for Unity Android apps using the
      IL2CPP scripting backend. To display symbolicated IL2CPP stack traces in
      the Crashlytics console, Android customers will need to upload symbol
      files for their builds. See the [Getting Started with Crashlytics Unity]
      (https://firebase.google.com/docs/crashlytics/get-started?platform=unity)
      Guild for more details.
    - Firestore: Fixed an issue where the `Equals()` and `GetHashCode()` methods
      of `DocumentSnapshot` would sometimes be inconsistent
      ([#8647](https://github.com/firebase/firebase-ios-sdk/pull/8647)).