[Feature] Bump OneSignal Android SDK version

[shepherd-l]

Description

One Line Summary

Updates included OneSignal Android SDK to 5.0.3.

Details

Motivation

Applies native Android fixes from the OneSignal Android SDK to the Unity SDK

• Fix Amazon purchase tracking setup
• Fix IAMs showing erroneously on every cold start

Testing

Manual testing

Tested OneSignal initialization, app build with Unity 2021.3.0f1 of the OneSignal example app on a emulated Pixel 4 with Android 12.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
• I have reviewed this PR myself, ensuring it meets each checklist item

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