Bump json from 2.2.0 to 2.3.1 in /ruby

Bumps [json](https://github.com/flori/json) from 2.2.0 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@v2.2.0...v2.3.1)

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

Author: dependabot[bot]

ruby/Gemfile.lock

@@ -16,7 +16,7 @@ GEM
       ffi (>= 1.3.0)
     ffi (1.11.1)
     jaro_winkler (1.5.3)
-    json (2.2.0)
+    json (2.3.1)
     method_source (0.9.2)
     parallel (1.17.0)
     parser (2.6.3.0)