Bump version to 8.3.0

[DordeDimitrijev]

• https://github.com/microsoft/react-native-code-push/pull/2707
• https://github.com/microsoft/react-native-code-push/pull/2471
• https://github.com/microsoft/react-native-code-push/pull/2562
• https://github.com/microsoft/react-native-code-push/pull/2705
• https://github.com/microsoft/react-native-code-push/pull/2697
• https://github.com/microsoft/react-native-code-push/pull/2719
• https://github.com/microsoft/react-native-code-push/pull/2558
• https://github.com/microsoft/react-native-code-push/pull/2720