Version 8.7.0
### 8.7.0:
- Changes
- General (iOS): Fixed an intermittent crash on iOS 15 caused by
constructing C++ objects during Objective-C's `+load` method.
([#706](https://github.com/firebase/firebase-cpp-sdk/pull/706))
([#783](https://github.com/firebase/firebase-cpp-sdk/pull/783))
- Crashlytics (Android): Fixed a bug that prevented some Crashlytics session
files from being removed after the session ended. All session-specific
files are now properly cleaned up.
([#737](https://github.com/firebase/firebase-cpp-sdk/issues/737))