Bump json from 2.19.1 to 2.19.9 in /docs (#134)

Bumps [json](https://github.com/ruby/json) from 2.19.1 to 2.19.9.
- [Release notes](https://github.com/ruby/json/releases)
- [Changelog](https://github.com/ruby/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v2.19.1...v2.19.9)

---
updated-dependencies:
- dependency-name: json
  dependency-version: 2.19.9
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -218,7 +218,7 @@ GEM
       gemoji (>= 3, < 5)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0, < 5.0)
-    json (2.19.1)
+    json (2.19.9)
     just-the-docs (0.12.0)
       jekyll (>= 3.8.5)
       jekyll-include-cache