chore(package): update flow-bin to version 0.121.0

Closes #70

Author: greenkeeper[bot]

package.json

@@ -60,7 +60,7 @@
     "chai-string": "^1.3.0",
     "eslint": "^4.1.0",
     "eslint-plugin-flowtype": "^2.29.2",
-    "flow-bin": "^0.61.0",
+    "flow-bin": "^0.121.0",
     "mocha": "^5.0.0",
     "nyc": "^11.0.1",
     "postcss": "^6.0.7",