Add Android 13 support

[bshvets8]

This PR adds support for a new Android 13 POST_NOTIFICATION permission that can be requested via the native requestPermissions method.

[PieterPicup]

@Vanethos Thanks for the great LIB. Could you please try get this in ASAP. With the release of A13 this will become a requirement for most apps very soon across a lot of devices.

For anyone who needs this now already you can import the branch directly for now from @bshvets8 repo using below in your pubspec.yaml
notification_permissions: git: url: https://github.com/bshvets8/flutter_notification_permissions.git ref: feature/android-13-support

[quedicesebas]

2 months...

[quedicesebas]

But not working for me, nothing happens after calling NotificationPermissions.requestNotificationPermissions