Merge bitcoindevkit/bdk#1054: ci: pin dependencies with Cargo update instead of in...

b6fecc8bc04e51c7f8d5a81580bd34c8ba6ab8cc ci: pin dependencies with Cargo update instead of in Cargo.toml (Steve Myers)

Pull request description:

  ### Description

  Remove 1.57.0 MSRV dependency pinning from Cargo.toml and use `cargo update --precise` method instead. This is how bdk 1.0.0 and other rust projects are doing it now.

  ### Notes to the reviewers

  This is needed to get the release/0.28 branch to build again. After it's merged I'll be able to start making the `0.28.1` release.

  ### Changelog notice

  none.

  ### 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:
  thunderbiscuit:
    ACK b6fecc8bc04e51c7f8d5a81580bd34c8ba6ab8cc. Neat fix.

Tree-SHA512: 67b78a29eefb247500b7f583ef7e928222fe0fe58464427739e7dcf83ec02ab9703f5cf5e760d60a2681ea0b11ae013aae291dc51b352d109e2100adb020a031