Frb upgrade

[BitcoinZavior]

[0.31.3]

Upgrades

• Updated Flutter and Rust dependencies to the latest version.
• Upgraded Gradle to version 8.4.0 and Java to version 17.
• Upgraded android-ndk to 26.3.11579264.

Fixed

• Removed unnecessary class exports.
• Resolved the txBuilder.setRecipients error.
• Resolved class incompatibility issues and renamed conflicting classes.

[erdemyerebasmaz]

Hey @StaxoLotl @BitcoinZavior,
Do you have an ETA for when a new bdk_flutter version compatible with flutter_rust_bridge 2.9.0 will be published on pub.dev?

Users who depend on multiple plugins built with flutter_rust_bridge are experiencing version conflicts.

This is currently a blocker for several of our users, any update would be highly appreciated.