chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

Author: greenkeeperio-bot

yarn.lock

@@ -1507,9 +1507,9 @@ flat-cache@^1.2.1:
     graceful-fs "^4.1.2"
     write "^0.2.1"
 
-flow-bin@0.50.0:
-  version "0.50.0"
-  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.50.0.tgz#d4cdb2430dee1a3599f0eb6fe551146e3027256a"
+flow-bin@0.51.0:
+  version "0.51.0"
+  resolved "https://registry.yarnpkg.com/flow-bin/-/flow-bin-0.51.0.tgz#97a3c511a17caa25d8fad58fc17aaabcb86319fe"
 
 follow-redirects@0.0.7:
   version "0.0.7"