Merge pull request #80 from travis-ci/dependabot/bundler/puma-4.3.9

Bump puma from 3.12.6 to 4.3.9

Author: DamianSzymanski

Gemfile.lock

@@ -46,10 +46,12 @@ GEM
     minitest (5.11.3)
     multipart-post (2.0.0)
     mustermann (1.0.3)
+    nio4r (2.5.8)
     pry (0.11.3)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.12.6)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-protection (2.0.3)
       rack