Merge bitcoindevkit/bdk#2194: ci: Fix pin-msrv

24e23e3a7d1f9a64dcf499f894c93af104a98bb9 ci: Fix pin-msrv (志宇)

Pull request description:

  ### Description

  MSRV broke again.

  ### Checklists

  #### All Submissions:

  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)

ACKs for top commit:
  LLFourn:
    ACK 24e23e3a7d1f9a64dcf499f894c93af104a98bb9

Tree-SHA512: 8e94f2eddabc1a403d227a4466bf94a55ee2fe06c1f97d581fe6a7a1039b4bfa156e08559e1b2263ee2cf205352eb1fe2ec819a76d7b081d2995f2804511f2db