Merge bitcoindevkit/bdk#1727: Use `bitcoin::constants::COINBASE_MATURITY`

309a6077d0fa263c03e5629568ae94844be0c90f fix(wallet, chain)!: use `bitcoin::constants::COINBASE_MATURITY` (Rob N)

Pull request description:

  Closes #1692

  #### 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

  #### New Features:

  * [ ] I've added tests for the new feature
  * [ ] I've added docs for the new feature

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [ ] I've added tests to reproduce the issue which are now passing
  * [ ] I'm linking the issue being fixed by this PR

ACKs for top commit:
  notmandatory:
    ACK 309a6077d0fa263c03e5629568ae94844be0c90f
  oleonardolima:
    ACK 309a6077d0fa263c03e5629568ae94844be0c90f

Tree-SHA512: 2e97ead256a34dff8130568e82b56214be975513a210b498ff8ac2d5fd7242d3f3d911d2ada8ce9ec04db4f5f87f9144ea1728784bd5c1581ee3b92a4c7188b7