Merge bitcoindevkit/bdk#825: Bump hwi to 0.4.0

4cad18bbcaa8199b82c10291aa38941f06823568 Bump hwi to 0.4.0 (Daniela Brozzoni)

Pull request description:

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  ### Description

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  ### Notes to the reviewers

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  ### Changelog notice

  - Bump hwi to 0.4.0

  ### 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 4cad18bbcaa8199b82c10291aa38941f06823568

Tree-SHA512: 6c73c091da743734ed87e4792f3c2a838ac7aa252388309ad46e017cc7e9b338bfdb7ed70925c8041a7d22a4d12e2a984e902619b1b7735c645e6c1b6855aeb3