Merge bitcoindevkit/bdk#495: Disable reqwest's default features

Merge bitcoindevkit/bdk#495: Disable reqwest's default features

380a4f2588cf9800bde739eb3ba58ca67b785291 Disable reqwest's default features (Thomas Eizinger)

Pull request description:

  ### Description

  By default, reqwest uses openssl for TLS. Any consumer wanting to use
  rustls will thus pull in unnecessary dependencies.

  ### 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

  #### New Features:

  * ~[ ] I've added tests for the new feature~
  * ~[ ] I've added docs for the new feature~
  * [x] I've updated `CHANGELOG.md`

  #### 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 380a4f2588cf9800bde739eb3ba58ca67b785291

Tree-SHA512: 17827fdd7656a1e97b4cc302bc3c4907a8493505c798fafd9b15fde12531a32cf60e7d63e878eb2001d6b3e95f7ae3da730e227eb85c73d9de55b56456cfb3a0