chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeperio-bot

yarn.lock

@@ -2114,9 +2114,9 @@ [email protected]:
   optionalDependencies:
     esdoc "^0.5.2"
 
-[email protected].3:
-  version "3.8.3"
-  resolved "https://registry.yarnpkg.com/danger/-/danger-3.8.3.tgz#0806d4307ab575e15cfa7320a3887cbcda1734d3"
+[email protected].4:
+  version "3.8.4"
+  resolved "https://registry.yarnpkg.com/danger/-/danger-3.8.4.tgz#e84b8398a3b7dd5707d7628a833f529efa4d1354"
   dependencies:
     "@octokit/rest" "^15.5.0"
     babel-polyfill "^6.23.0"