Version 8.8.0

### 8.8.0
- Changes
    - General (iOS): Another possible fix for an intermittent crash on iOS 15
      caused by constructing C++ objects during Objective-C's `+load` method.
    - Storage: Added a method to access the url of a storage instance.
    - Crashlytics (Android): Updated internal Crashpad version to commit
      `281ba7`. With this change, disabling tagged pointers is no longer
      required, so the following can be removed from your manifest's
      application tag: `android:allowNativeHeapPointerTagging=false`.
    - Crashlytics (Android): Improved runtime efficiency of the
      [`SetCustomKey` functions](/docs/crashlytics/customize-crash-reports?platform=unity#add-keys),
      significantly reducing the number objects created and disk writes when
      keys are updated frequently.
    - Remote Config: Fixed an issue where the TimeSpan field of FetchDataAsync
      was being used incorrectly.