chore(package): update eslint-plugin-flowtype to version 3.13.0

Closes #16

Author: greenkeeper[bot]

package.json

@@ -28,7 +28,7 @@
         "eslint": "^4.6.1",
         "eslint-config-google": "^0.10.0",
         "eslint-plugin-import": "^2.8.0",
-        "eslint-plugin-flowtype": "^2.39.1",
+        "eslint-plugin-flowtype": "^3.13.0",
         "babel-cli": "^6.24.1",
         "babel-core": "^6.25.0",
         "babel-eslint": "^10.0.1",