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

@@ -246,7 +246,7 @@ GEM
       rails-dom-testing (>= 1, < 3)
       railties (>= 4.2.0)
       thor (>= 0.14, < 2.0)
-    json (2.9.0)
+    json (2.9.1)
     launchy (2.5.2)
       addressable (~> 2.8)
     logger (1.6.1)