Update flow version

Author: basicdays

package.json

@@ -34,7 +34,7 @@
     "babel-register": "^6.18.0",
     "chai": "^3.5.0",
     "eslint": "^3.12.1",
-    "flow-bin": "^0.37.0",
+    "flow-bin": "^0.38.0",
     "mocha": "^3.2.0",
     "nyc": "^10.0.0",
     "source-map-support": "^0.4.6"