build(deps): bump json from 1.7.7 to 2.3.1

Bumps [json](https://github.com/flori/json) from 1.7.7 to 2.3.1.
- [Release notes](https://github.com/flori/json/releases)
- [Changelog](https://github.com/flori/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v1.7.7...v2.3.1)

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

Author: dependabot[bot]

Gemfile.lock

@@ -55,7 +55,7 @@ GEM
       multipart-post (~> 1.1)
     hashie (2.0.2)
     i18n (0.6.4)
-    json (1.7.7)
+    json (2.3.1)
     kitchen-lxc (0.0.1.beta1)
       test-kitchen (>= 1.0.0.alpha.0)
     method_source (0.8.1)