Merge pull request #36 from libtcod/dependabot/bundler/json-2.21.2

Bump json from 2.20.0 to 2.21.2

Author: HexDecimal

Gemfile.lock

@@ -221,7 +221,7 @@ GEM
       gemoji (>= 3, < 5)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0, < 5.0)
-    json (2.20.0)
+    json (2.21.2)
     kramdown (2.4.0)
       rexml
     kramdown-parser-gfm (1.1.0)