Merge pull request #509 from scala-js/dependabot/bundler/json-2.3.1

Bump json from 2.1.0 to 2.3.1

Author: sjrd

Gemfile.lock

@@ -43,7 +43,7 @@ GEM
       sass (~> 3.4)
     jekyll-watch (2.1.2)
       listen (~> 3.0)
-    json (2.1.0)
+    json (2.3.1)
     kramdown (1.17.0)
     liquid (4.0.1)
     listen (3.1.5)