chore(package): update eslint-plugin-flowtype to version 3.3.0

Closes #38

Author: greenkeeper[bot]

package.json

@@ -22,7 +22,7 @@
     "babel-preset-flow": "^6.23.0",
     "codecov": "^3.0.0",
     "eslint": "^4.3.0",
-    "eslint-plugin-flowtype": "^2.34.0",
+    "eslint-plugin-flowtype": "^3.3.0",
     "flow-bin": "^0.75.0",
     "greenkeeper-lockfile": "1",
     "jest": "^22.0.0",