Merge pull request #3667 from Coursemology/dependabot/bundler/puma-4.2.1

Bump puma from 4.2.0 to 4.2.1

Author: trangmei

Gemfile.lock

@@ -327,7 +327,7 @@ GEM
     multi_json (1.13.1)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
-    nio4r (2.5.1)
+    nio4r (2.5.2)
     nokogiri (1.10.4)
       mini_portile2 (~> 2.4.0)
     nokogumbo (2.0.1)
@@ -357,7 +357,7 @@ GEM
       activerecord (>= 3.0)
     progress (3.5.2)
     public_suffix (4.0.1)
-    puma (4.2.0)
+    puma (4.2.1)
       nio4r (~> 2.0)
     rack (2.0.7)
     rack-proxy (0.6.5)