Merge #1590: ci: pin tokio-util dependency version to build with rust 1.63

ea6876b 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

  <!-- In this section you can include notes directed to the reviewers, like explaining why some parts
  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 ea6876b

Tree-SHA512: f200dc753fabe993bf926506e213d16050808b00eeb9c2d36fbd45cb62e0611300c660839ea37e17b0513cba2a5da48321e186d173d2871b45d2fce266f4f2b0

Author: evanlinjin

.github/workflows/cont_integration.yml

@@ -48,6 +48,7 @@ jobs:
           cargo update -p url --precise "2.5.0"
           cargo update -p cc --precise "1.0.105"
           cargo update -p tokio --precise "1.38.1"
+          cargo update -p tokio-util --precise "0.7.11"
       - name: Build
         run: cargo build ${{ matrix.features }}
       - name: Test

README.md

@@ -75,6 +75,7 @@ cargo update -p proptest --precise "1.2.0"
 cargo update -p url --precise "2.5.0"
 cargo update -p cc --precise "1.0.105"
 cargo update -p tokio --precise "1.38.1"
+cargo update -p tokio-util --precise "0.7.11"
 ```
 
 ## License