[in_app_purchase] Bumps in_app_purchase_android minimum version to 0.2.3

[bparrishMines]

Bumps in_app_purchase_android minimum version to 0.2.3. This version of in_app_purchase_android upgrades the Google Play Billing Library from 3.0.2 to 5.0, which is a requirement for the Google Play store: https://developer.android.com/google/play/billing/deprecation-faq

Successor to #6525

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[stuartmorgan-g]

LGTM, thanks!

[stuartmorgan-g]

For posterity, the motivation for doing this even though it's not strictly required by the app-facing package (which is normally the only time we update minimum dependency versions, as it reduces client flexibility) is that this has been a fairly common point of confusion among clients who aren't regularly updating their transitive dependencies due to the store-level warning. See flutter/flutter#113012, flutter/flutter#112184, flutter/flutter#111368, flutter/flutter#111261, flutter/flutter#110742.