Release 5.2.2

[jennantilla]

:wrench: Maintenance

• chore: add warning for identity verification in https://github.com/OneSignal/OneSignal-Flutter-SDK/pull/901

  🔧 Update Android SDK from 5.1.15 to 5.1.17

• release notes
• Fix "could not be instantiated" exception when; some modules are omitted AND android.enableR8.fullMode is enabled. https://github.com/OneSignal/OneSignal-Android-SDK/pull/2136

  🔧 Update iOS SDK from 5.2.1 to 5.2.2

• release notes
• Prevent In-App Message request crashes by making null values safe https://github.com/OneSignal/OneSignal-iOS-SDK/pull/1457
• Add Dispatch Queues to all executors to prevent concurrency crashes https://github.com/OneSignal/OneSignal-iOS-SDK/pull/1454
• Fix clearing notifications incorrectly such as when pulling down the notification center https://github.com/OneSignal/OneSignal-iOS-SDK/pull/1451

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This change is 

[jennantilla]

@nan-li @jkasten2 heads up I didn't notice this approved PR so merged it in and updated release notes