Bump json from 2.9.0 to 2.9.1

Bumps [json](https://github.com/ruby/json) from 2.9.0 to 2.9.1.
- [Release notes](https://github.com/ruby/json/releases)
- [Changelog](https://github.com/ruby/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v2.9.0...v2.9.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -223,7 +223,7 @@ GEM
     irb (1.14.3)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
-    json (2.9.0)
+    json (2.9.1)
     json-schema (4.3.0)
       addressable (>= 2.8)
     kramdown (2.5.1)