Merge bitcoindevkit/bdk#1674: ci: pin deps for MSRV

d2771502cee0179941aec3f11d97d9bc8137fb3d ci: pin deps for MSRV (valued mammal)

Pull request description:

  Pin deps in CI to build on MSRV

  - pin `indexmap` to 2.5.0
  - pin `security-framework-sys` to 2.11.1

  ### 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 d2771502cee0179941aec3f11d97d9bc8137fb3d

Tree-SHA512: adc15c5487f78a211892c4e6a851e17b04c3d02cc73ef2af25cf97a6e8c5aab9f80b14a4e05c409b76670bf6b35a04d10880ae0f2d3becfc28185e74a6311699