Merge pull request #450 from matestack/dependabot/bundler/builder/puma-3.12.6

Bump puma from 3.12.4 to 3.12.6 in /builder

Author: jonasjabari

builder/Gemfile.lock

@@ -86,7 +86,7 @@ GEM
     nio4r (2.5.2)
     nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.4)
+    puma (3.12.6)
     rack (2.2.3)
     rack-proxy (0.6.5)
       rack