Update just-the-docs requirement from 0.11.1 to 0.12.0

Updates the requirements on [just-the-docs](https://github.com/just-the-docs/just-the-docs) to permit the latest version.
- [Release notes](https://github.com/just-the-docs/just-the-docs/releases)
- [Changelog](https://github.com/just-the-docs/just-the-docs/blob/main/CHANGELOG.md)
- [Commits](just-the-docs/just-the-docs@v0.11.1...v0.12.0)

---
updated-dependencies:
- dependency-name: just-the-docs
  dependency-version: 0.12.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile

@@ -3,5 +3,5 @@ source 'https://rubygems.org'
 gem "jekyll", "~> 4.4.1" # installed by `gem jekyll`
 # gem "webrick"        # required when using Ruby >= 3 and Jekyll <= 4.2.2
 
-gem "just-the-docs", "0.11.1" # pinned to the current release
+gem "just-the-docs", "0.12.0" # pinned to the current release
 # gem "just-the-docs"        # always download the latest release