chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeperio-bot

yarn.lock

@@ -1216,9 +1216,9 @@ bser@^2.0.0:
   dependencies:
     node-int64 "^0.4.0"
 
-buffer@5.0.8:
-  version "5.0.8"
-  resolved "https://registry.yarnpkg.com/buffer/-/buffer-5.0.8.tgz#84daa52e7cf2fa8ce4195bc5cf0f7809e0930b24"
+buffer@5.1.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/buffer/-/buffer-5.1.0.tgz#c913e43678c7cb7c8bd16afbcddb6c5505e8f9fe"
   dependencies:
     base64-js "^1.0.2"
     ieee754 "^1.1.4"