Merge #190: chore: update README rust version badge to 1.75.0

0103e4b chore: update README rust version badge to 1.75.0 (Steve Myers)

Pull request description:

  ### Description

  Update README rust version badge to 1.75.0.

  ### Notes to the reviewers

  I forgot to do this on the last release.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk-cli/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  tvpeter:
    ACK 0103e4b

Tree-SHA512: cf6707e837cdeceb1c15ffd8170106b627f38e41bf0044ae196c99d4ebd529f27d3b17f8413e574ed361ae29d8906e20a8cadfd07fce6129942b1fd6eb0c389b

Author: notmandatory

README.md

@@ -13,7 +13,7 @@
     <a href="https://github.com/bitcoindevkit/bdk-cli/actions?query=workflow%3ACI"><img alt="CI Status" src="https://github.com/bitcoindevkit/bdk-cli/workflows/CI/badge.svg"></a>
     <a href="https://codecov.io/gh/bitcoindevkit/bdk-cli"><img src="https://codecov.io/gh/bitcoindevkit/bdk-cli/branch/master/graph/badge.svg"/></a>
     <a href="https://docs.rs/bdk-cli"><img alt="API Docs" src="https://img.shields.io/badge/docs.rs-bdk_cli-green"/></a>
-    <a href="https://blog.rust-lang.org/2021/12/02/Rust-1.57.0.html"><img alt="Rustc Version 1.57.0+" src="https://img.shields.io/badge/rustc-1.57.0%2B-lightgrey.svg"/></a>
+    <a href="https://blog.rust-lang.org/2023/12/28/Rust-1.75.0/"><img alt="Rustc Version 1.75.0+" src="https://img.shields.io/badge/rustc-1.75.0%2B-lightgrey.svg"/></a>
     <a href="https://discord.gg/d7NkDKm"><img alt="Chat on Discord" src="https://img.shields.io/discord/753336465005608961?logo=discord"></a>
   </p>