Bump json from 2.7.6 to 2.8.1 (#24)

Bumps [json](https://github.com/ruby/json) from 2.7.6 to 2.8.1.
- [Release notes](https://github.com/ruby/json/releases)
- [Changelog](https://github.com/ruby/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v2.7.6...v2.8.1)

---
updated-dependencies:
- dependency-name: json
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -71,7 +71,7 @@ GEM
       jekyll (>= 3.8, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    json (2.7.6)
+    json (2.8.1)
     just-the-docs (0.10.0)
       jekyll (>= 3.8.5)
       jekyll-include-cache