Merge bitcoindevkit/bdk#822: Update ci nightly-docs workflow to use nightly-2022...

9ddd5025382341a5e941630473563edc593645f4 Update ci nightly-docs workflow to use nightly-2022-12-14 (Steve Myers)

Pull request description:

  ### Description

  The current nightly version we were using for the nightly-docs workflow is failing so I updated it to tonight's (2022-12-14)
  version.

  ### Notes to the reviewers

  I decided to select another hard-coded date nightly version so we don't run the risk of some random nightly release breaking this workflow.

  ### 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:
  danielabrozzoni:
    utACK 9ddd5025382341a5e941630473563edc593645f4

Tree-SHA512: 650fc4880c1de37f3cd581ba1e2f416ac732d06e03b1dea2878b5051bf38ff809dd965baa0987c7ce47e5aa5e30932cedad3dce17fca6b787e6ace72d604c591