[in_app_purchase] Update Play Billing library to 7.1.1

[mchudy]

Updates Play Billing Library to the latest version 7.1.1. Exposes new APIs as per release notes:

• Adds Dart representation of ProductDetails.InstallmentPlanDetails
• Adds Dart representation of PendingPurchasesParams and removes the deprecated enablePendingPurchases method on BillingClientWrapper (breaking change)
• Adds Dart representation of Purchase.PendingPurchaseUpdate
• Removes the deprecated ProrationMode as it has been removed from the native library (breaking change)

This PR introduces breaking changes in in_app_purchase_android, but does not introduce any breaking changes on the platform interface level.

Fixes flutter/flutter#147394

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages repo does use dart format.)
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or this PR is exempt from version changes.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or this PR is exempt from CHANGELOG changes.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

[stuartmorgan]

@reidbaker Ping on this review

[reidbaker]

@gmackall I am not going to get to this. Deferring to you for review.

[wph144]

The billingClient version upgrade process must proceed as quickly as possible.
Older versions of billingClient cause a low probability of missing payments after a certain period of time.
This may result in cases where the consumer makes a payment but does not receive the service for that payment, so the billingClient version upgrade must be done quickly.

Currently, in_app_purchase 3.2.0 is using billingClient 6.2.0,
and billingClient 7.0.0 version was distributed in May 2024,
so it has now taken more than 7 months.
I hope this gets merged quickly.

[gmackall]

Mostly LGTM, added a couple comments. Sorry for the delay on review

[mchudy]

CI is complaining about versioning, but I believe we should first publish the new version of in_app_purchase_android and only once that lands on pub update the dependency in the base package? Or can this be handled inside a single PR?

[stuartmorgan]

CI is complaining about versioning, but I believe we should first publish the new version of in_app_purchase_android and only once that lands on pub update the dependency in the base package? Or can this be handled inside a single PR?

See https://github.com/flutter/flutter/blob/master/docs/ecosystem/contributing/README.md#changing-federated-plugins for the process of landing a multi-package PR with interdependencies.

[stuartmorgan]

This would be a breaking change for in_app_purchase when rolling the dependency there; we strongly prefer not dropping OS support before the SDK itself.

In this case, Flutter 3.24+ only supports Android SDK 21+, so the way to make this change would be to update the plugin's min SDK version to 3.24, which makes this no longer a breaking change.