Bump json from 2.1.0 to 2.3.1 (#9)

Bumps [json](https://github.com/flori/json) from 2.1.0 to 2.3.1.
- [Release notes](https://github.com/flori/json/releases)
- [Changelog](https://github.com/flori/json/blob/master/CHANGES.md)
- [Commits](https://github.com/flori/json/compare/v2.1.0...v2.3.1)

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

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

Gemfile.lock

@@ -30,7 +30,7 @@ GEM
     hashie (4.1.0)
     i18n (1.8.2)
       concurrent-ruby (~> 1.0)
-    json (2.1.0)
+    json (2.3.1)
     json-jwt (1.12.0)
       activesupport (>= 4.2)
       aes_key_wrap