Prepare for PUP 1.8.1's release pt. 2.

PiperOrigin-RevId: 473781234

Prepare for 1.8.0 release pt 2.

PiperOrigin-RevId: 458522014

Prepare for Integrity API's release.

PiperOrigin-RevId: 429335897

Update CHANGELOG.md and package.json files for 1.6.1 release

PiperOrigin-RevId: 423873943

Update README to include additional instructions git clone users

Users who git clone the repo into their Unity projects will need to also install the External Dependency Manager for Unity in order to download necessary Java dependencies like Play Core.

PiperOrigin-RevId: 410702377

Internal change

PiperOrigin-RevId: 381308505

Fix some build warnings

Mostly these were about removing unused fields.

PiperOrigin-RevId: 362547797

Remove unnecessary warning

This change removes the warning log: "An instance of PlayAssetDeliveryEventHandler is already present in the scene. Self Destructing..."

PiperOrigin-RevId: 335074673

Remove inner experimental #ifdefs.

PiperOrigin-RevId: 323677067

Update com.google.play.billing change log

PiperOrigin-RevId: 315338296