Merge pull request #394 from matestack/dependabot/bundler/builder/puma-3.12.4

Bump puma from 3.12.2 to 3.12.4 in /builder

Author: pascalwengerter

builder/Gemfile.lock

@@ -86,7 +86,7 @@ GEM
     nio4r (2.5.2)
     nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.3)
+    puma (3.12.4)
     rack (2.1.2)
     rack-proxy (0.6.5)
       rack