Merge bitcoindevkit/bdk#1590: ci: pin `tokio-util` dependency version to build with...

ea6876b70eb2b1ca9ee73e5719f1a9850e11827c ci: pin `tokio-util` dependency version to build with rust 1.63 (Wei Chen)

Pull request description:

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  ### Description

  <!-- Describe the purpose of this PR, what's being adding and/or fixed -->
  `tokio-util` version 0.7.12 raised `msrv` to 1.70.
  The previous version 0.7.11 was pinned to CI to continue working.

  ### Notes to the reviewers

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  of the PR were done in a specific way -->

  ### Changelog notice

  <!-- Notice the release manager should include in the release tag message changelog -->
  <!-- See https://keepachangelog.com/en/1.0.0/ for examples -->
  * Pinned tokio-util dependency version to build with rust 1.63.

  ### 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:
  evanlinjin:
    ACK ea6876b70eb2b1ca9ee73e5719f1a9850e11827c

Tree-SHA512: f200dc753fabe993bf926506e213d16050808b00eeb9c2d36fbd45cb62e0611300c660839ea37e17b0513cba2a5da48321e186d173d2871b45d2fce266f4f2b0