chore(package): update eslint-plugin-flowtype to version 3.1.1

Closes #153

Author: greenkeeper[bot]

package.json

@@ -66,7 +66,7 @@
     "enzyme-adapter-react-16": "^1.0.4",
     "eslint": "^5.0.0",
     "eslint-config-react-app": "^2.0.0",
-    "eslint-plugin-flowtype": "^2.33.0",
+    "eslint-plugin-flowtype": "^3.1.1",
     "eslint-plugin-import": "^2.2.0",
     "eslint-plugin-jsx-a11y": "^6.0.3",
     "eslint-plugin-react": "^7.0.1",