Merge bitcoindevkit/bdk#1749: chore: Revert `rustls` pin dependency

8e5a7c67c0c6be4da259e6015e9a7575df0f1385 chore: Revert `rustls` pin dependency (志宇)

Pull request description:

  ### Description

  The recent release of `rustls` (0.23.19) reverts it's MSRV to 1.63 so the pin is no longer necessary.

  ### Notes to the reviewers

  Some context:
  * https://github.com/bitcoindevkit/rust-electrum-client/pull/158
  * https://github.com/rustls/rustls/pull/2244

  ### Changelog notice

  * Revert MSRV pin of `rustls`.

  ### 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:
  LagginTimes:
    ACK 8e5a7c67c0c6be4da259e6015e9a7575df0f1385
  ValuedMammal:
    ACK 8e5a7c67c0c6be4da259e6015e9a7575df0f1385

Tree-SHA512: 355291f93a879effc8aa1d7fe0254d8f879f26d06f0d6b0ad3d7a508a53179f7c5b9ebcd2d450ee042fbd2867119cf9a15c3193af6f36c3e5548634ce689cdca