Merge bitcoindevkit/bdk#1789: Change default tx to version 2

2219b7cd55bfb8023e9b426de0ef118b32bfa372 fix(tx_builder): change default tx to version 2 (benalleng)

Pull request description:

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  ### Description

  Changes the default version number to version 2 to enchance privacy for the type of wallet used

  Fixes #1676

  ### Changelog notice

  - Changed the default transaction version number in the transaction builder.
  - Updated the test to test for the default transaction number.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  notmandatory:
    ACK 2219b7cd55bfb8023e9b426de0ef118b32bfa372

Tree-SHA512: 76a2d394318eea94a99c033c3df14d64dbcf96c0f91dba91d2e337b9ecf78302af3d535ab11a74ed7372a521d3bc14c3455b7c8266d79d2995cc7c5da363b426

diff --cc crates/wallet/src/wallet/mod.rs
Simple merge