Bump json from 2.1.0 to 2.3.0

Bumps [json](https://github.com/flori/json) from 2.1.0 to 2.3.0.
- [Release notes](https://github.com/flori/json/releases)
- [Changelog](https://github.com/flori/json/blob/master/CHANGES.md)
- [Commits](ruby/json@v2.1.0...v2.3.0)

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

Gemfile.lock

@@ -5,7 +5,7 @@ GEM
     httparty (0.16.3)
       mime-types (~> 3.0)
       multi_xml (>= 0.5.2)
-    json (2.1.0)
+    json (2.3.0)
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)